The office is very clean because_{(A clean office and two year old building are unrelated)} the building was built two years ago.
The working room is divided by low* partitions as high* as you can see your college_{(spelling: colleague)} in front of you if you stand but you can't if you sit down.
                                               *These words contradict each other.
About 20 desks take up the half space of the working room. There are several vacant seats because some people are always working on a project which is going on at_{(choice of preposition)} the other room.

There are a few office supplies - a water purifier, and a small paper shredder and a business machine that equips all print, Fax, scan and copy functions.
                                                                                                                                                        *that prints, faxes, scans and makes copies.
My office has windows in_{(preposition choice)} only one side of the wall but the windows are big enough to give us a lot of light.

I share an office space with 20 other co-workers but they work so quiet_(quietly) that you can hear only_{(can only hear)} the sound of tapping keyboards.
Besides, nowadays they communicate with customers using a computer messenger program instead of using telephones.

But I can tell you I love my office atmosphere because I can concentrate on my work.

CORECTIONS Displayed:

My office was built two years ago and is very clean.
The working room is divided by low partitions that separate you and your colleague in front of you, but if you stand you can see them.
                                              
About 20 desks take up the half space of the working room. There are several vacant seats because some people are always working on a project which is going on in the other room.

There are a few office supplies - a water purifier a small paper shredder and a business machine that that prints, faxes, scans and makes copies.
                                                                                                                                                       
My office has windows on only one side of the wall but the windows are big enough to give us a lot of light.

I share an office space with 20 other co-workers but they work so quietly that you can only hear the sound of tapping keyboards.
Besides, nowadays they communicate with customers using a computer messenger program instead of using telephones.

I can tell you I love my office atmosphere because I can concentrate on my work.

.