Learn Turkish: Bu iş daha önemli. - This job is more important.

Just like in English, you put daha directly in front of the adjective. Because önemli means important, putting daha before it creates daha önemli, meaning more important.

Where is the word for "is" in this sentence?

There isn't one! In Turkish, the present tense "is" for "he", "she", "it", or "this" is usually invisible. You simply say Bu iş daha önemli (literally "This job more important") and the "is" is naturally understood by the listener.

What does the -li at the end of önemli mean?

The suffix -li means "with" or "having". The root word önem means "importance". By adding -li, you get önemli, which literally means "having importance" or simply "important".

Could iş also be translated as "work" instead of "job"?

Yes! The word iş is very flexible. Depending on the context, it can mean job, work, task, or even business. Translating this sentence as "This work is more important" is also perfectly correct.