You must have knowledge of current. As current is the charge per unit time.
Resistance is the obstruction offered to the flow of current.
Reason: As charge (electrons) flow through the wire (conductor), electrons collide with the walls of the conductor and they also collide with each other. Due to this collision, obstruction occurs and this is called resistance.
Let us understand the concept of resistance with a common daily life experience:
Suppose, you are walking at a place where there is no person, it means you are free to move. Now suppose you are moving at delhi or mumbai railway station, then what will happen? You will face lots of people and you will now face obstruction for your movements. This is basically resistance.