This is the 6227th most frequent Catalan word.
mateu
"Mateu" is the Catalan word for "Matthew," a given name.
In this sentence, 'mateu' is a verb meaning 'crush' in the imperative form directed at 'you' (second person plural).
Mateu les ametlles abans de barrejar-les amb la massa.
Crush the almonds before mixing them with the dough.
Here, 'mateu' is a verb in the subjunctive mood, expressing a hypothetical or required action to 'defeat' directed at 'you' (second person plural).
És important que mateu l'enemic en tots els jocs de rol.
It is important that you defeat the enemy in all role-playing games.
In this case, 'Mateu' is used as a proper noun, referring to a common male name in Catalonia.