This is the 228th most frequent Icelandic word.
þú
The Icelandic word "þú" means "you" (singular, informal).
Here, 'þú' is used as the subject pronoun in the nominative case to directly address a single person informally.
Þú ert frábær kennari.
You are a great teacher.
In this sentence, 'þér' is the dative case form of 'þú,' used as an object specifying the person addressed.
Má ég fá hjálp frá þér?
May I receive help from you?
Here, 'þér' again appears in the dative case, showing a formal and polite gesture towards the person addressed.