Learn Polish: Przygotowujemy długoterminową współpracę. - We are preparing long-term cooperation.

It is formed from the adjective długi (long) and the noun termin (term/date), plus the adjective suffix -owy. The -o- is a standard linking vowel used in Polish to connect two roots into a single compound word, creating the base form długoterminowy.

Why does the adjective długoterminową end in -ą here?

It is modifying the feminine noun współpracę in the accusative case, because it acts as the direct object of the verb przygotowujemy (we are preparing). Compound adjectives decline exactly like simple adjectives, so it takes the standard feminine accusative ending -ą.

The noun współpracę looks like a compound too. What does the współ- part signify?

The prefix współ- is very common and means 'co-' or 'together'. Attached to praca (work), it literally forms 'co-work' or 'cooperation'. The compound declines exactly like the base feminine noun praca, which is why it takes the accusative ending -ę in this sentence.

Why does this sentence use the imperfective verb przygotowujemy rather than its perfective pair przygotujemy?

Using the imperfective przygotowujemy emphasizes an ongoing, present process: 'we are preparing' it right now. If you used the perfective przygotujemy, the meaning would shift entirely to the future tense: 'we will prepare' (and successfully finish preparing) the cooperation.