A body can be negatively charged by

A body can be negatively charged (giving electrons to it, removing some electrons from it, giving some protons to it, removing some neutrons from it.)

Electrons flow from a positively charged body to a negatively charged body when connected by a copper wire.

When a body is negatively charged by friction, it means

When a body becomes negatively charged. Its mass.

When a body becomes negatively charged, its mass

When a slide body is negatively charged by friction, it means that the body has

A body is negatively charged means