It is wanting what others have, desiring to possess what they possess. You can be envious of tangible and intangible things, including their wealth, their good looks and their innate intelligence.
Envy is often an ‘identity’ thing, as the underlying dynamic is not so much about wanting the things they have as wanting to be like them. Envy in such cases becomes generalized, from thing to the whole person.
Envy can sometimes be moderately positive, such as when you grudgingly admire what a friend has achieved, but do not like them any less as a result.
The most common form of coping with envy is, after recognizing it, taking a philosophical approach that says something like ‘This is silly. Life is too short to waste my energy on this thing’. See Identity and dreams; Identity and Sex; Want Wanted Wanting