talking about time
If something happens before a time or event, it happens earlier than that time or event.
We arrived just before two o'clock.
Before the First World War, farmers used horses instead of tractors.
You also use before when you are talking about the past and you want to refer to an earlier period of time. For example, if you are describing events that took place in 2010, you refer to 2009 as ‘the year before’.
They had met in Bonn the weekend before.
They had forgotten the argument of the night before.
You use before last to refer to a period of time that came before the last one of its kind. For example, if today is Wednesday 18th September, you refer to Friday 13th September as ‘last Friday’, and Friday 6th September as ‘the Friday before last’.
We met them on a camping holiday the year before last.
I have not slept since the night before last.
talking about position
Before is sometimes used to mean in front of'. This is a formal or old-fashioned use. It is more common to use in front of with the same meaning.
He stood before the door leading to the cellar.
She stood in front of a mirror, combing her hair.**
You use before or in front of when you are talking about the order in which things appear in speech or writing. For example, if you are describing the spelling of the word ‘friend’, you can say that the letter ‘i’ comes before or in front of the letter ‘e’.
If you are giving someone directions, and you say that one place is a certain distance before another place, you mean that they will come to the first place first. Don't use ‘in front of’ with this meaning.
The turning is about two kilometres before the roundabout.