As with the Roman alphabet, which you may be familiar with it (since you are using it to read this answer), different letters have different symmetries.
Not many. Depending on how you write, the letters L, O, Q, and X can have diagonal lines of symmetry.
In caps there is 1. lower case none.
zero, all the keys have different letters, numbers, or symbols
the answer is U O S H K Z X N A D=2 0R MORE LINES OF SYMMETRY
4 Lines of symmetry
Not many. Depending on how you write, the letters L, O, Q, and X can have diagonal lines of symmetry.
Pi has 2 lines of symmetry
None.
O and X And H and I (Note "O" has many, actually an infinite number of, lines of symmetry)
Five.H , I , O , X( ' O ' has 2 lines of symmetry and more besides and ' X ' has 4 )
H,I,O,X Note that if you draw "O" as a perfect circle, it will have infinitely many lines of symmetry.
Seven
None. Some letters have one or more but all the letters, taken as a set, have none.
In caps there is 1. lower case none.
zero, all the keys have different letters, numbers, or symbols
the answer is U O S H K Z X N A D=2 0R MORE LINES OF SYMMETRY
it has five lines of symmetry