It’s not the most musical way to improve your playing but it can give you a good warm up and can help to steadily develop your technique/ dexterity over longer periods of time so that you don’t have to try so hard physically when trying to play different ideas.
The idea is that you learn all the combinations of 1 2 3 4 . So going through them logically first: 1234, 1243, 1324, 1342, 1432, 1423 and then the same starting on 2 so 2134, 2143, 2314, 2341 etc…then from 3 and from 4. Try writing them all out.
Then using that pattern you can use it in different ways to get your fingers and picking used to different movements.
It looks like a lot to learn!!! …but once you memorise the pattern it becomes automatic and you can try it through different scales/ chord inversions etc to make your technique more fluent.