Question

What is a nucleophilic attack?

Answer 1

The donation of electrons from an electron-rich portion of a molecule (this can be a lone pair, or even electrons already involved in bonds) to an electron-poor part of either the same, or a different molecule. The electron rich “donor” is called a nucleophile, and the electron poor “acceptor” is called an electrophile. This “attack” or “donation” usually results in the formation of a bond between the nucleophile and electrophile

Arrows are usually drawn to indicate the direction of “attack”. In this case the electrons are coming from the :Nu and going to the C+. Thus the :Nu is “attacking” the C+, and acting as a nucleophile.