If something happens before a particular date, time, or event, it happens earlier than that date, time, or event.
If you do one thing before doing something else, you do it earlier than the other thing.
You use before when you are talking about time. For example, if something happened the day before a particular date or event, it happened during the previous day.
If you do something before someone else can do something, you do it when they have not yet done it.
If someone has done something before, they have done it on a previous occasion. If someone has not done something before, they have never done it.
If there is a period of time or if several things are done before something happens, it takes that amount of time or effort for this thing to happen.
If a particular situation has to happen before something else happens, this situation must happen or exist in order for the other thing to happen.
If someone is before something, they are in front of it.
If you tell someone that one place is a certain distance before another, you mean that they will come to the first place first.
If you appear or come before an official person or group, you go there and answer questions.
If something happens before a particular person or group, it is seen by or happens while this person or this group is present.
If you have something such as a journey, a task, or a stage of your life before you, you must do it or live through it in the future.
When you want to say that one person or thing is more important than another, you can say that they come before the other person or thing.
14. before long -> see long