I’m still a beginner myself so if I get anything wrong someone please jump in and correct me but my understanding of ある is roughly translated ‘to exist’. Which in most cases would translate to english as “There is …”
So a simple sentence would be: 「カフェがある」 or “There is a cafe”.
As well as ある, there’s also いる which serves the same purpose. The difference is that ある is used for inanimate objects and いる is used for animate objects.
Eg. 「犬(いぬ)がいる」“There is a dog”.
あります and います are just the more polite forms of these verbs.
The sentence you linked broken down is: 大学(だいがく) - university, に - particle used for locations to show where something exists, カフェ - cafe, が - particle to inform you the subject of the sentence is what came before it, ありました - to exist said politely, the た at the end lets you know the sentence is in past tense.
So if you put that all together you get “University at, cafe there was.” or in english order “There was a cafe at the university.”