The Cambodian language is Khmer, which is inherited itself – and advanced in education with application of Indic languages Pali and Sangkrit from India.
Also, the Khmer language is influenced by spoken and written Thai. Some technical languages are borrowed from French. However, English is commonly communicated in hotels and business compounds at present days.
English and French are popular second languages and Chinese is the third.
See also Learn Khmer Language