Parts of Speech Discussion

After the practice of eight part of speech, I have leant that there are lots of things I don't know.

In the sentence,

After, that- conjunction

the - article

practice, part, speech, things - Nouns

have learnt, are, don't know - verb

I - pronoun

of - preposition

I confuse the words 'there' and 'lots of'. I wonder if someone tells me.