English is an SVO (= Subject - Verb - Object) language.
Tuvan is an SOV (= Subject - Object - Verb) language.
Notice that the pronoun "мен" (= I) is used not only in the beginning of the sentence, but also at the end of the sentence. For a sentence to be considered grammatically correct, the first "мен" is optional but the second "мен" is obligatory.
This is a perfectly grammatical sentence:
How do you make a choice whether to keep the optional "мен" or not? As far as I know, it does not matter in conversations. However, in songs, the choice may be influenced by the need to match the first letters of each line in a verse (head rhyme) and the need to have a certain number of syllables in each line.
In the song «Үжелээн бис, дөртелээн бис», each verse starts with two similar sentences. These sentences do not have verbs but still end with the obligatory second "бис" (= we).
It is possible to add the first "бис," the subject, and the sentences will still be grammatical.
Thus, Tuvan is an SOV language where subjects like "мен" or "бис" are repeated at the end of a sentence. While "мен" or "бис" in the beginning is optional, "мен" or "бис" at the end of a sentence is obligatory.
Cultural note:
In Tuvan poetry, in addition to the requirement to rhyme the last words in each line (end rhyme), you are often expected to match the first letters in each line (head rhyme). To check this rule, you can go back and reread the lyrics. Song #1 and Song #2 closely follow this rule, while Song #3, a more modern song, deviates from the rhyming rules from time to time.
You can go to Part 2 Song 1 if you want to continue exploring the Tuvan numerals.
You can go to Part 2 Song 3 if you want to continue learning the vocabulary for family members and occupations.