"That gesture relates to the Italian language."

Translation: Tiu gesto rilatas al la itala lingvo.

[NerdyMatthew]

[BoshlankH]

Could 'de' be used instead of 'al' here?

[Gresillon.org]

"rilati" is a transitive verb with accusative.
The best use is: « Tiu gesto rilatas la italaN lingvoN. »
The other correct use is: « Tiu gesto rilata AL la itala lingvo. »
In English, the verb is used with the proposition "to rilate to", so the course use this form.

[MaxKrieger]

Why doesn't "la italan" instead of "la itala lingvo" work here?

[andrewgtreantos]

Why "tiu" and not "tio"?

[Gresillon.org]

In «Tiu gesto rilatas al la itala lingvo», the subject is «Tiu gesto», especially «gesto».
One could use «tio» instead of «tiu gesto», the sentence becomes «Tio rilatas al la itala lingvo», which is a correct sentence, but not the good translation.

Tio = that, Tio ĉi = this. These are words with ending "o" and can be used as subject (or object).

Tiu gesto = that gesture, Tiu ĉi gesto = this gesture. Tiu (ĉiu, kiu, iu, neniu) are normally linked with a noun like "gesto" and can not be used alone as subject (or object)

[arkpofadisto]

I'd say every gesture is related to Italian language