This could have a big impact on Reddit's eco-system.
As per Engadget, the trending content platform is testing out a new option which would enable users to offer real money 'tips' to creators, providing a whole new motivation for Redditors to post.

As you can see here, the new process would offer suggested tipping amounts, though users would be able to select the 'Other' option to tip anything up to $100 dollars. You then connect your credit card (if one is not already linked to your account), and you can pay that creator real-world dollars - as opposed to 'Karma', Reddit's current on-platform credit system (which holds no monetary value).
At present, the option is only available on a single subreddit, for a single user, so it's very early in the trial stage, but the current process sees Reddit taking an 18.5% cut of any payment, with a small percentage also going to Stripe, which is facilitating the payments.
And as noted, if it is rolled out more broadly, it could have a major impact on Reddit's platform. Currently, Reddit users compete for Karma, which is essentially bragging rights for their overall on-platform status. But even that - without the added financial incentive - has its downfalls. For example, prominent Reddit user u/GallowBoob - whose real name is Robert Allam - is regularly criticized over the tactics he uses to boost his Karma score, which include re-posting popular posts from other users into other, larger subreddits and re-purposing other people's content into different formats to suck up more upvotes.
In Reddit's current state, this is not a major concern, because Karma points don't really mean anything. Yes, such conduct is morally questionable, but there's nothing really on the line - the original poster isn't losing anything, in real-world terms, by having their content essentially stolen.
But if money were involved, that would become a concern. With the added incentive of actual payment, Redditors would no doubt take larger issue with having their content re-published, and seeing other users profit from the same. Reddit could avoid much of the blame here by putting the onus onto users - it'll be the users themselves that choose who to tip and who not to, not them, so the audience would decide whether the reward re-posters or not. But still, you can imagine this being a can of worms for Reddit to deal with, if implemented on a broader scale.
But it would give Reddit a means to offer payment to the many moderators and creators who do contribute regularly. One of Reddit's biggest strengths is in human moderation - look through the list of the most upvoted content on any given day and you're likely to see a much more engaging stream than you'll get on any other platform, curated, endorsed and supported by real people, as opposed to an algorithm.
Facebook has tried to provide similar through algorithmic means, but it hasn't been able to come close to Reddit's listings, and much of the work in facilitating that is done by volunteer Redditors who are passionate about their chosen subjects and communities. A tipping system would give them a means to generate actual revenue from their efforts, which would no doubt provide significant motivation for them to continue, and help Reddit boost its eco-system.
Worth noting, too, that other platforms have already implemented creator tipping. Twitch has 'Cheering', YouTube has 'Super Chat' (below), while Facebook added a tipping option for gaming streamers last year.

There is precedent for such a system, and it can be a viable way to provide real-world payments for creators. But it does change the dynamic somewhat - which, in the case of Reddit, could be a significant concern, and could add a significant amount of administration work for the platform to deal with.
That's no doubt why Reddit is starting slow. As noted, right now this is a very small trial, an experiment to see what users think, and what problems might arise, before Reddit likely broadens the test pool and gets more real-world responses.
On the positive side, it could strengthen Reddit's communities and see more content pumped through its network, while also prompting more users to promote their on-platform presences, expanding Reddit's reach. But on the negative, there are various elements which could become problematic.
Reddit will no doubt be evaluating all of these in the coming months.