Learn Russian: У нас есть два урока.

This is the special rule for counting in Russian! After the numbers два (2), три (3), and четыре (4), Russian requires the noun to be in the Genitive singular case, rather than a normal plural. The dictionary form of the word is урок, and its Genitive singular form is урока.

Why do we use два for 'two' here instead of две?

The Russian word for 'two' changes depending on the gender of the noun it counts. You use два with masculine and neuter nouns, but две with feminine nouns. Since урок is a masculine noun (because it ends in a consonant), we must use два.

Word-for-word, how does У нас есть translate to 'We have'?

Russian doesn't usually use a direct verb for 'to have'. Instead, it literally says 'At us exists.' У means 'at' or 'by', нас is the required form of мы (we) after the word у, and есть means 'is' or 'exists'.

Should есть change to a plural form since there are two lessons?