For those who don't understand it's Arabic:

As-salamu alaykum (Arabic: ٱلسَّلَامُ عَلَيْكُمْ, as-salāmu ʿalaykum, Arabic: [as.sa.laː.mu ʕa.laj.kum] (listen)), also written salamun alaykum and typically rendered in English as salam alaykum, is a greeting in Arabic that means 'Peace be upon you'. The salām (سَلَام, meaning 'peace') has become a religious salutation for Muslims[1][2] worldwide when greeting each other, though its use as a greeting pre-dates Islam, and is also common among Arabic speakers of other religions (such as Arab Christians and Mizrahi Jews).

Sauce: wiki