Translation:The students always study the Latin language.
Studeo requires the dative when it means to support, to encourage. Otherwise it's transitive. https://www.online-latin-dictionary.com/latin-english-dictionary.php?parola=Studeo
The verb "studeo" raquires the dative case. Both the noun "lingua" and the adjective "latina" belong to the first declension. So in dative case you would say linguae latinae or latinae linguae. For instance, linguae latinae studeo.
Other verbes require the causative case, e.g "disco". Linguam latinam disco.
I hope this helps.
I am always a little weary of sites like the one that was linked in that comment. The idioms, examples and such at the bottom of the link in the comment are mostly with the dative from what I saw. Maybe that dictionary is using the convention some books I have seen do, where verbs that take the dative have definitions with 'to' or 'for' at the end. Maybe the usage of the accusative became more common post classical Latin, the usage to mean 'to study' seems more common in later Latin. The site also has an entry for studeor, a passive of studeo, but I don't think I have ever seen a passive form of studeo before.
Every book I have that I could find that mentions studeo, studere (Wheelock's, Pocket OLD, LLPSI) states it is used with the dative (in general, not for some meanings instead of others). I have most often seen it described as usually taking the dative.
For a more nuanced explanation I looked at Lewis and Short briefly. Based on Lewis and Short it can occur with just an accusative, but this is said to be rare and usually is a pronoun or an adjective. They give that it is frequent to see an infinitive with an accusative. They also state that with the dative is the most frequent usage.
This may be a case of new vs old usage. Most of the resources I use tend to focus on classical Latin.