Learn Hardcore Russian: Я наслаждаюсь концертом.

It means "I am enjoying the concert" (or simply "I enjoy the concert"). The sentence communicates that the speaker is currently experiencing pleasure or delight from the concert.

Why is the noun "концерт" changed to "концертом" in this sentence?

In Russian, the verb наслаждаться requires its object to be in the instrumental case. That is why концерт becomes концертом, indicating the means or entity through which the enjoyment is experienced.

How is the verb наслаждаться conjugated in the first person singular present tense in this sentence?

Наслаждаться is a reflexive verb. In the first person singular present tense, it is conjugated as я наслаждаюсь. The ending ‑юсь shows both the proper conjugation for я and indicates its reflexive nature.

Can наслаждаться be used with other nouns in a similar construction?

Yes, it can. You can express enjoying various activities or objects by keeping the same pattern: the subject + наслаждаться + [noun in the instrumental case]. For example, "Я наслаждаюсь книгой" means "I am enjoying the book," where книгой is the instrumental form of книга.