Potassium is in the first column and therefore has 1 electron in its outermost shell. It would tend to lose one electron and form a +1 ion.

Is K negative or positive ion?

Potassium is the major cation (positive ion) inside animal cells, while sodium is the major cation outside animal cells.

What does K+ mean?

The chemical notation for potassium is K+. The proper level of potassium is essential for normal cell function.