Learn Hardcore Hausa: Shin kin yarda mu fara karatu tun yanzu, ko za mu jira zuwa gobe? - Do you feminine agree that we start studying right now, or will we wait until tomorrow?

Shin is a yes/no question marker. It signals that what follows is being asked as a question (similar to starting with Do you…? / Are you…? in English).
It’s common in careful or neutral speech, though in everyday Hausa you can sometimes ask yes/no questions just with intonation (rising tone) and omit shin.

Why is it kin yarda and not ka yarda or ki yarda?

kin is the subject pronoun + tense/aspect marker used for 2nd person singular feminine (you, speaking to a woman/girl) in this kind of verb clause.

kin yarda = you (f.) agreed / you (f.) accept / you (f.) are willing
If speaking to a man/boy, you’d usually use ka: Shin ka yarda…?
ki can appear in other structures (often imperative/subjunctive contexts), but here the sentence is using the normal finite clause pattern with kin.

What exactly does yarda mean here?

yarda means to agree / to consent / to accept / to be willing. In this sentence, it’s essentially Are you willing to…? / Do you agree that…?
So it’s not just “agree” in an argument sense; it can also mean be okay with or consent to a plan.

Why is mu used after yarda?