M'agrada l'olor del pa al forn.

A helpful word-by-word breakdown is:

• M'agrada = it pleases me / I like
• l'olor = the smell
• del pa = of the bread / often just of bread in natural English
• al forn = in the oven / oven-baked, depending on context

So the Catalan structure is basically:

[To me] [is pleasing] [the smell] [of the bread] [in the oven].

Because agradar does not work like English to like.

In Catalan, agradar literally means something like to be pleasing to. So:

• M'agrada l'olor... = The smell ... is pleasing to me
• Natural English translation: I like the smell...

This is why the person who likes something is not the grammatical subject in the same way as in English.

m' is the shortened form of em, which means to me.

Before a vowel, em usually contracts:

• em agrada → m'agrada
• em interessa → m'interessa

So in this sentence, m' means to me.

Because the verb agrees with l'olor, which is singular.

With agradar, the verb matches the thing that is pleasing, not the person experiencing it.

Here:

• l'olor = singular
• so: agrada

Compare:

• M'agrada l'olor = I like the smell
• M'agraden les olors = I like the smells

Because olor is a feminine noun, so the full article is la, but before a vowel Catalan normally shortens the article to l'.

So:

• la olor → l'olor

This is the same kind of elision you see in:

• l'aigua
• l'amiga
• l'home

So yes, olor is feminine, even though English learners may not expect that.

del is a contraction of de + el.

So:

• de el pa → del pa

It means of the bread.

This kind of contraction is very common in Catalan:

• del = de + el
• al = a + el

Catalan uses the definite article more often than English does.

So del pa can be perfectly natural where English would simply say bread:

• l'olor del pa → the smell of bread

In this sentence, del pa sounds like the smell belonging to or coming from the bread. If you said olor de pa, that would often feel more like a bread smell or something that smells like bread.

So del pa is the more natural choice here for the smell of the bread / of bread.

al is a + el, so literally al forn is to the oven or at the oven, but in cooking expressions it often corresponds to natural English in the oven or oven-baked.

Here, pa al forn is understood as bread that is in the oven or associated with oven baking. So the sentence means the speaker likes the smell of bread as it bakes.

Most naturally, al forn goes with pa, not with olor.

In standard spelling, with a following vowel, you normally write M'agrada, not Em agrada.

The full form is em, but before a vowel it contracts:

• em + agrada → m'agrada

So for this exact sentence, M'agrada is the correct written form.