Swap - Buy & Sell - Profit ?

Hello i see alot of wallets do quick buy & sell and make a small profit by that ... Do anyone do this ? What's the name for that and why does it work so good ? Wallets has so many trades like that is crazy ...

So my Questions are how does it work ? Is here anyone who do this or did this ? Is this also possible in spot trading ?

This wallets has also alot of trades usually from large cash to small positions like buy for 100 $ sell for 136 $ basically in a second just in and out lol ...

I was thinking this is possible only with large cash size but my example shows it's possible also with small amounts ... Please clarify me about this type of trading thanks crypto community love you ????