Hi Roxi, this is very well written and I don't see any gramatical errors. My suggestions are only about words or frases that might sound a bit more natural.

Best of Luck!

Motivation letter

Dear Sir/Madam,
I would like to express my interest in being part of the Partial FCT Europe-Program.
I am currently studying Dietetics and Nutrition and I think this is an excellent opportunity to improve my professional skills and to acquire working experience.
I have studied English language in Argentina, my birth country, and I have always thought this kind of
experience would be a challenging and positive way to improve my english abilities as well. Since I left my country and settled down in Spain, I have discovered inner resources that helped me to adapt to the culture of another country.
Even though my work experience is mainly in the field of customer service and education, I would like to change and redirect my professional career to the field of dietetics and nutrition.
I love nutrition and everything regarding this topic. In my free time I like to read nutrition articles in english and I also like to chat via Skype with english speakers.
Thank you for taking the time to consider my application.
Hoping that my request has a favourable response, I remain at your disposal.
Yours sincerely,