Learn Croatian: Ovi studenti su isti. - These students are the same.

Ovaj means "this" for masculine singular nouns. Because we are talking about multiple students (studenti), the word for "this" changes to its plural form, ovi, meaning "these".

How do we know studenti is plural?

In Croatian, masculine nouns usually form their plural by adding an -i to the end of the singular word. So, one student is student, and multiple students are studenti.

Why is the verb su placed where it is?

Su is a short word called an enclitic that generally must go in the second position of a sentence. Here, the whole phrase ovi studenti acts as the first block of information, so su comes directly after it.

Why does the adjective isti end in -i here?

Adjectives must match the noun they describe in gender and number. Because studenti is a masculine plural noun, the adjective takes the masculine plural form, making it isti.