Breakdown of Þú mátt leggja á bílastæðinu.
þú
you
á
onto / on / in (static location) / on (a day of the week)
mega
to be allowed to
leggja
to park
Questions & Answers about Þú mátt leggja á bílastæðinu.
Why is the verb mátt instead of má?
Mátt is the þú (you, singular) form of the modal verb mega, which means 'may' or 'to be allowed to'. You only use má with 'I', 'he', 'she', or 'it'.
Is there a missing að before leggja?
No, it is correct as is! Because mega is a modal verb, the verb that follows it (leggja) must be a bare infinitive. Just like in English where we say 'You may park' instead of 'You may to park', you never put að after mega.
Doesn't leggja usually mean 'to lay' or 'to put'?
Yes, it normally means to lay something down. However, it is the standard verb used for parking a vehicle. The full phrase is leggja bílnum (to park the car), but Icelanders usually shorten it to just leggja when the context is obvious.
Why is the word for parking lot bílastæðinu here instead of just bílastæði?
Two things are happening at the end of this word. First, the preposition á triggers the dative case because it describes a stationary location (where you are parking). Second, the -nu at the end is the attached word for 'the', making it 'the parking lot' in the dative case rather than just 'a parking lot'.