This is the 4977th most frequent German word.
am
"Am" is the contraction of "an dem," meaning "at the" or "on the" in English, depending on context.
In this sentence, 'am' is the contraction of 'an dem,' which indicates the preposition 'an' ('at') combined with the definite article 'dem' ('the') to specify location in the masculine/neuter dative case.
Ich bin am Strand.
I am at the beach.
Here, 'am' again combines 'an' ('on') with 'dem' ('the') to denote working near or at the computer, indicating a spatial relationship.
Er arbeitet am Computer.
He works on the computer.
This usage of 'am' is a colloquial way in German to describe an ongoing action ('am Lachen' - 'laughing'), combining 'an' ('on') with 'dem' ('the') followed by an infinitive noun-like verb.