Putting words together
There is a problem
Children are constantly advised to think before they speak, to consider the likely effect of some idea on one or more listeners, to be simple and candid, or to be politely indirect. But the actual words are another matter.
In “There is a problem”, what is the word there doing? Speakers don’t think about it. It is forced by English syntax which requires an overt subject before the word which specifies the tense, present is, as in this case, as opposed to past was. There does this job without referring to anything more specific. It doesn’t need to be thought about in advance.
But even the child hears an enormous number of such sentences, the structure here is hard to learn.