What is the meaning of Trolling?

present participle and gerund of troll

The act of one who trolls (in various senses).

A fishing technique in which one or more baited fishing lines are dragged by a moving boat. Not to be confused with trawling, which drags a net.

trolling (act of a person who posts deliberately offensive or provocative messages online)

trolling (fishing technique in which one or more baited fishing lines are dragged by a moving boat)

Source: wiktionary.org