Suki na dake desu

I don't understand the use of the “na” in the expression “suki na dake desu”

Thanks in advance for your answer

こんにちは (Konnichiwa) Abgueguen,

Thanks for your question. 

Since すき (suki) is a な (na) adjective, you need to add the particle な (na) when using it to modify the thing that comes after it. In this case, すき (suki) “like” modifies that word だけ (dake) “just,” so we need to add the particle な (na) after すき (suki) to join these two together.

If you want to learn more about how to use adjectives to modify, you can check out these lessons:

https://app.rocketlanguages.com/members/products/5/lesson/5110

https://app.rocketlanguages.com/members/products/22/lesson/5243

I hope this helped. Please let me know if you have any other questions.

勉強を頑張ってください！ (Benkyō o ganbatte kudasai!)