In English grammar,
there is [was] / there are [were] are differentiated based on the following noun.
(A) There is [was] an apple on the table.
(B) There are [were] apples on the table.
if the noun is singular, there is [noun] + somewhere.
if the nous is plural, there are [noun]s + somewhere.
In a casual conversation, native speakers often use them in constracted forms. --- there's / there're
When I listen to their talking, however, I often hear them saying "there's lots of ( a lot of ) + [plural nouns].
(A) There's a lot of people out there.
(B) There's lots of useful things he can read on the internet.
According to native speakers, "there're a lot of ----" is kind of hard to pronunce,
so they use
"there's a lot of --- / There's lots of ----" instead.
It's a good thing to know that English grammar is not always true