Question

why only metal donates electron ?​

Answer 1

Explanation:

because they have excess electron by which they get donate and get stable configuration of respective noble gas

Answer 2

Answer:

You should only use that definition in the context of ionic compounds. To form ionic compounds, you typically want to ‘transfer electrons completely’ (high school terminology) from one element to the other and thereby create charged compounds.

Typically, these charged ions are energetically least unfavourable if they display the so-called noble gas configuration — valence electrons like the closest noble gas. Now if you remember that the periodic table ‘wraps around’ (sodium is the element following neon), it may make sense that it is easiest for some elements termed metals to give off electrons to achieve this state, while others, termed non-metals, have an easier time gaining electrons for the same purpose.

This, however, is as permeakra verbosely wrote, a crude generalisation and only valid in the high-school ionic-bond context.