The script is beautiful but complex. It has 33 consonants and 24 vowels (plus additional "personal" vowels), which can be daunting for beginners.
Unlike Thai, Vietnamese, or Mandarin, Khmer is NOT a tonal language . You don't have to worry about the pitch of your voice changing the entire meaning of a word. Learn Khmer (Cambodian)
Reaching an advanced level where you can discuss complex ideas typically takes 1 to 2 years of consistent practice. Top Ways to Learn The script is beautiful but complex
Because Khmer isn't on mainstream apps like Duolingo, you’ll need to look at more specialized resources: 1. Language Schools & Study Groups immersion is your best friend.
If you are physically in Cambodia, immersion is your best friend.