Yuri mode is explained in detail in this post. But in general yes! The point is to make a lesbian-only playthrough more comfortable, esp. compared to SS!
You can unlock all lesbian sex moves with just lesbian sex (in normal mode you need to do footjobs and anal sex to unlock two of the moves). Semen potions are removed from the game entirely and replaced with “essence” potions. You can still have sex with men if you want to, though, and some light sexual content with men may still be present where it makes sense.