Learn Dutch: Het ontbijt is smakelijk. - The breakfast is appetizing.

Ontbijt (breakfast) is a neuter noun in Dutch, which means it must take the definite article het. There isn't a strict rule for why meals get certain articles, so it is best to memorize it as a pair: het ontbijt.

I usually say lekker when food is good. Can I use lekker here instead of smakelijk?

Yes, absolutely! You will hear Het ontbijt is lekker very often in daily life. Smakelijk is just a slightly more descriptive or formal way to say "tasty" or "appetizing."

Is this the same word used when people say Eet smakelijk?

Exactly! When you tell someone Eet smakelijk before a meal, you are literally saying "eat tastily." It is the standard Dutch way to say "enjoy your meal" or "bon appétit."

How is the word smakelijk built?

It comes from the noun de smaak, which means "the taste" or "the flavor." The suffix -elijk is added to turn it into an adjective, much like adding "-y" to "taste" in English to get "tasty."