Question

NA contains positive charge and electron is a subatomic particle with negative elementary charge . So , how can NA be an electron donor?

Answer 1

By NA do you mean Na (sodium)?
Sodium is not positively charged in its ground state. It has 11 electrons in its atom and needs to lose one to attain noble gas configuration.
After losing one electron (a negatively charged species) it becomes positive (since now protons are more than the electrons so a positive charge).