Answer:
2AgNO3 + 2Li --> 2LiNO3 + 2Ag is balanced because the amounts of each chemical is equal on each side. There are 2 Ag on each side, thus being equal and why the 2 is infront of each chemical with Ag in it. There are 2 Li on eachside, equal/ balanced. 2 NO3 on each side, you get it now. Think of balanced as also equal, so make sure all chemicals on each side are equal.
Here is a website if you need help with balancing equation, I hope it helps! Another tip (sorry for all the text), is to thing of each chemical as a ingredient in a sandwhich. If you want two sandwiches with the same amount of ingredients each, then you need to “balance” the ingredients so that you have the same amount of ingredients for each sandwich.
Have a good day!