I found the maps for my car navigation system (Seat Leon) RNS510/810 - V9 (2012) maps and somewhere it says Phoneme: yes
What does this mean guys? Can I still use the dvd for maps? Thanks in advance

It means phonetics. The proper pronunciation of your language.

By default computer voices pronounce all in the same way.
The phoneme data is used to correct words that otherwise come out of your speaker in a way that is hard to understand.
They also handle special commands on some systems, like change the voice attributes - for example to make a warning sound more urgent.

Thank you guys for your kind answer. Really appreciate it!

You're welcome!