When (in world) you are looking at some block and press binded keybind, inventory interface will open with recipe of this block showing. Or press other keybind, it shows uses of this block.

Also third keybind to toggle fluid "visibility" for this feature. When disabled and you use keybind on clay block below water, it will show clay block recipe. But when eneblad it will show water creation sources (if are). Would be helpful for some fluids, like oil, etc.