~
Means Spaces (Pattern), Recent Page or Field
In a Pattern, ~ (tilde) means to look for zero or more spaces.
At the Visual home line, the ~ (tilde) command means display the page that you most recently left. It actually corresponds to the Visual current line "*". So, it can be used from line-mode to reference that line.
The tilde is also used in Visual mode as a field separator within text lines that are to be divided (VV) or glued (GG).