Let me explain the meaning of 4 commonly used words/ phrases (whose origin lies in Arabic) :
1. ASSALAAM ALAIKUM : A common greeting among Muslims meaning "Peace be with you" or "Peace be upon you".
This greeting is returned by 'Walaikum assalaam' which means "Peace be upon you too". A simple 'Walaikum' means "same to you"
Extended forms include "Assalamu alaikum wa rahmatullah" (May the peace and mercy of Allah be with you) and "Assalamu alaikum wa rahmatullahi wa barakatuhu" (May the peace, mercy, and blessings of Allah be with you).
The 'salaam' used here is not the same in meaning as its counterpart in Hindi/ Urdu. This is an Arabic word meaning 'Peace'.