1. Highlight A11
2. Ctrl-C to copy
3. Select destination cell (ex: A2)
4. Ctrl-V to paste
Or you could use an array formula. Say you have data in A11 (4
cells)
Select four vertical cells (ex: A4:A7) and type =TRANSPOSE(A11), hit
ctrl-shift-enter because this is an array formula. Then paste in the
values and delete the original cells.
I suppose that would depend on whether you want the letters rotated or
normal. Format/cell/alignment will turn the letters with the direction
of text. There's also an option there on the left of the "compass" that
will stack your letters.