Tense is a term which refers to the time a given verb took place; i.e. present, past, or future. 


In Greek, tense tells you both time and aspect. The major tenses in Greek are:

Tense Tense Formative Augment
Present no no
Imperfect no yes
First Aorist yes yes
Second Aorist no yes
Future yes no
Perfect yes no


Hebrew verbs show time in different ways.  more