When this program executes, the computer will check all conditions in order until one of them matches its concept of truth. As soon as this occurs, the program will execute the statement immediately following the condition and continue on, without checking any other condition for truth. For this reason, when you are trying to optimize a program, it is a good idea to sort your if-else conditions in descending probability. This will ensure that in the most common scenarios, the computer has to do less work, as it will most likely only have to check one or two "branches" before it finds the statement which it should execute. However, when writing programs for the first time, try not to think about this too much lest you find yourself undertaking premature optimization.
Having said all that, you should be aware that an optimizing compiler might rearrange your if statement at will when the statement in question is free from side effects. Among other techniques optimizing compilers might even apply jump tables and binary searches.