I can explain in 2 ways about "imasu". First, if it is a independent verb "imasu", it can be translated as "there is / are (living things)" as some people have already explained. Although, I can add another translation. For example, Heya ni neko ga imasu. "There is a cat/ cats in the room." Neko wa heya ni imasu. "The cat is in the room" So it depends on the situation when you use "there is +Subject+Place ." translation or "Subject + is/are + place". If "imasu" is used with other verbs for compound verb such as "tabete imasu ", "sunde imasu", "warete imasu", it adds something about the state of the verb. Ex, continuity "tabete imasu = be eating" , state "nihon ni sundeimasu = I live in Japan.", continuity of effect "garasu(glass) ga warete imasu= the glass is broken". We should treat the verb "imasu" separately devided into an independent verb and a kind of a "sub verb".

By itself, it can be used as "there is" for example neko ga imasu There is a cat. With this form, the thing that exists must always have a "ga" after it. Imasu in this case is used with living, moving, things. For things that are inanimate "arimasu" is used instead. hon ga arimasu There is a book. when "imasu" is used as the main verb in a sentence, it means "there is/are...," there exist(s)..." when talking about people, animals, etc.

IMASU is like there is/are. but only used to person,, not to things ;)

IMASU - some like THERE IS/ARE....and it is used with....life objects. For example... There is a cat under the tree. Ki no shita ni neko ga imasu. I'm Russian))...and I don't know how to explain this clearly in English))...Sorry)))....But I hope you'll understand me))....If we talk about something we have (a pet) or...someone we see/know...and we want to say that this object is...situated somewhere...we'll say IMASU...but only with LIFE OBJECTS... I HAVE GOT a cat - Watashi wa neko ga IMASU. THERE ARE children in the garden - Niwa ni kodomo ga IMASU. Hmm.....I hope you'll understand))....if you have more questions...write me & I'll try to help you)))

I don't speak Japanese fluently, I am a beginner, but I don't think it has a literal translation. It is more of like English adding "ing" to a word. I think. Hope it helps. I will check back to see if you get a better answer.