"You must walk."
Translation:Tá oraibh siúl.
Why is it siul and not siulann? So confused on that entire section, they breezed through it.
Siúl is the verbal noun (roughly analogous to an English infinitive or gerund) of the verb siúil, while siúlann is a conjugation of siúil. The sentence’s literal translation is “Is on-you to-walk” — it translates as “must” because Irish doesn’t have a wealth of modals.