Learn Turkish: Bu teknik çok hızlı ama tehlikeli. - This technique is very fast but dangerous.

In Turkish, you often don't need a verb for simple descriptions. The sentence structure itself implies 'is'. In formal writing, you might see the suffix -dir attached to the last word (tehlikelidir), but in everyday Turkish, simply ending with the adjective tehlikeli is perfectly natural for saying 'is dangerous'.

How are the adjectives 'hızlı' and 'tehlikeli' formed?

Both of these words use the very common -li suffix, which turns a noun into an adjective meaning 'having' or 'with' that thing. The noun hız means 'speed', so hızlı means 'having speed' (fast). The noun tehlike means 'danger', so tehlikeli means 'having danger' (dangerous).

Where is the reciprocal verb suffix from this lesson?

This specific sentence doesn't contain the -(I)ş suffix because there are no verbs in it at all! It is a descriptive sentence built entirely of nouns and adjectives. Since the lesson's target grammar only attaches to verb roots, it doesn't appear in 'to be' sentences like this one.