That looks to me like green hair algae. A small amount is natural but if it’s all over your tank, then there is an imbalance causing it (usually too much light and/or nutrients)
There is a couple approaches to make it go away:
1. Get a critter that eats it (this is the least effective way, think of it like using a bandaid when you need stitches).
2. Remove it by hand.
3. The best way is to figure out what is causing your tank to be out of balance, fix it, and starve the algae.
If it’s all over your tank look into doing a 72 hour blackout period.