A useful Russian word I learnt recently is ага (aga) [ɐˈɡa/ɐˈɣa], it is an interjection similar to yep, yeah, aha and uh-huh in English. It shows that you’re listening, but don’t necessarily agree with the speaker.
Here are some examples of usage:
– Окей, ага, круто = Okay. All right. That’s cool.
– Ага, я так и думала = Here, I’ll show it to you.
– Ага, я слышу тебя = Uh yeah, I can hear you.
– Вероятно, лучше думать таким образом, ага = It’s probably best to think of it that way, yeah.
Synonyms include:
– да (da) = yes, but, really
– так (tak) = so, thus; like that; so much; just so, then, well, yes
– угу (ugu) = yep, yeah
Sources: Wiktionary, Reverso, bab.la
I love ага, угу and ого! I find them interesting because the spelling is only an approximation of the pronunciation. (This is true of the corresponding words in English too). I’ve heard that the [ɣ] in ага is more of a Southern Russian accent, while [x] is common in a General Russian accent. However, I think Russian Wiktionary comes the closest to what people actually say with [ɐˈʕa]: two low vowels with the corresponding pharyngeal semivowel in between. As for угу, Wiktionary may disagree but I’ve heard Russians in person and on Forvo pronounce it like English “mhm” with the mouth completely closed.