The words opposite and across from mean that something is located at the other side of something.

The bank is opposite the post office. or The bank is across from the post office.

Henry sat opposite me at the table. or Henry sat across from me at the table.

The expression in front of simply means that one thing is closer to a point of reference (the "front" of an area, or the point of view of the person looking).

I stood in front of the bank.

He sat in front of me in the classroom.

The word before can be used for location/position, but it is somewhat rare and more formal. Instead, before is typically used for time or for position in a sequence:

We need to pack our bags before leaving for the airport.

The letter i comes before the letter e in the word "friend." or position in a sequence

Most Dangerous Dog Breeds

Perro de Presa Canario

The Perro de Presa Canario is a large dog that was originally bred for working livestock. The name of the breed is Spanish and it means Canarian catch dog . Presas require early socialization and obedience training. In some situations, the Presa can be aggressive toward other dogs and suspicious of strangers.