The phrase is two words - not one and translates literally as más o menos but it is not used to mean "so-so" as I think más o menos might be, for example in answer to a question - "how was the party? More or less is mostly used to mean "approximately"

We use "more or less" when we are not sure of something or define something specifically. But is quite close the "subject in discussion" like for example : The box weighs 50 pounds, more or less. ( we are not sure of the quantity here, so we use "more or less" to give an approximate quantity. more or less -> approximate/ around / close to