This may seem mysterious, because you have letters and numbers, but no one has told you what the letters stand for. 5a is easy if we know that a=2. 5a would equal 5x2 = 10 (another way to write that is 5*2=10)
In your question, you have many letters that are variables. a, b, c and v are your variables. The good news is that we don't have to know what numbers they represent in order to combine like terms. Combining like terms is another way of organizing the numbers. To use a picture, we can put all the apples with the other apples, bananas with the other bananas, and pizzas with the other pizzas.
We started with 11b -6 6v 5a 5c 6 -5b 2b
- all the numbers with a --- 5a
- all the numbers with b --- 11b, -5b, 2b
- all the numbers with c --- 5c
- all the numbers with v --- 6v
- all the numbers with no variable --- 6, -6
Now that we have organized, we know what we can combine. There is no way for us to combine v+b. That's ok. The numbers with a, c, and v have no like terms. Nothing matches them.
We can combine the numbers with b. 11b - 5b +2b = 8b
We can combine the numbers with no variable 6-6=0
We are left with 5a, 8b, 5c, 6v