There is a...(если первое подлежащее после оборота в форме ед.числа)
Examples: there is a table in my room;
there is a capboard near the door in my room.
There are...(если подлежащее во мн.числе)
Examples:there are three bookshelves above the table in my room;
there are some pictures and posts on the right wall of my room.