In electrical engineering or physics, resistance is the ability of a substance or an electrical circuit to stop the flow of an electrical current through it.
In a country which is occupied by the army of another country, or which has a very harsh and strict government, the resistance is an organized group of people who are involved in illegal activities against the people in power.
If you take the line of least resistance in a situation, you do what is easiest, even though you think that it may not be the right thing to do. In American English, you usually talk about the path of least resistance .