The first conditional is a structure used to express the consequence of an action or an event.
An illustrative example is "If I get a raise I will buy a new car".
- If ... present simple, ... will ...
The second part of the conditional has the modal verb "will".
Example: If it rains tonight I'll stay at home.
Note that the order of the two parts may be changed: I will lend it to you if I find it.