Learn Hardcore Turkish: Sıcak ekmeği hemen yiyebilmek çok güzel. - It is very nice to be able to eat hot bread right away.

That -i is the accusative case marker. In Turkish, a direct object that’s definite or specific gets -ı/-i/-u/-ü (according to vowel harmony). Here you mean “the hot bread” (a particular loaf), so you say sıcak ekmeği. If you spoke of hot bread in general—“hot bread is delicious,” for example—you’d leave it in the nominative: sıcak ekmek.

What does hemen mean, and why does it come before yiyebilmek?

hemen means “immediately” or “right away.” In Turkish, adverbs are quite flexible but often appear just before the verb (or infinitive) they modify. So in sıcak ekmeği hemen yiyebilmek, hemen directly qualifies yiyebilmek, giving “to be able to eat (it) immediately.”

What is yiyebilmek? It looks like more than one verb.

It’s a single infinitive verb built from three parts:

ye- (the root for “eat”)
-yebil- (the potential suffix meaning “can/be able to”)
-mek (the infinitive ending)
Putting them together—ye
- yebil
  - mek—yields yiyebilmek: “to be able to eat.”

Why is it yiyebilmek and not yemebilmek?

The base verb is yemek (“to eat”), with stem ye-. When you attach a suffix beginning with a vowel (like -ebil), Turkish inserts a buffer y to avoid a vowel cluster:
ye + yebil → yeyebil, which naturally simplifies to yiyebil.
Hence yiyebilmek is the correct form.

How can Sıcak ekmeği hemen yiyebilmek act as the subject of the sentence?

In Turkish, verbs in the -mek/-mak form (infinitives) can be nominalized—treated like nouns. The entire phrase Sıcak ekmeği hemen yiyebilmek means “being able to eat hot bread right away.” It functions as the subject (or topic) of the predicate çok güzel (“very nice”).

Why isn’t there a verb like olmak (“to be”) or a copula here?

Turkish often omits the copula in simple statements. An adjective can stand alone as the predicate. So çok güzel directly means “(it is) very nice.” You could add olmak or -dir for emphasis or formality—Çok güzeldir—but in everyday usage it’s dropped.

Could I rewrite it without the ability suffix -ebil? What changes?

Yes. If you say
Sıcak ekmeği hemen yemek çok güzel.
you’ve replaced yiyebilmek (“to be able to eat”) with yemek (“to eat”). The sentence now means “Eating hot bread right away is very nice,” whereas the original emphasizes the ability or opportunity to eat it immediately.

Is the word order strict here? Could I move hemen or çok around?

Turkish word order is fairly flexible, especially for adverbs and degree words. You might hear:
• Hemen sıcak ekmeği yiyebilmek çok güzel.
• Sıcak ekmeği yiyebilmek çok güzel hemen.
but the most natural is
Sıcak ekmeği hemen yiyebilmek çok güzel.
Generally, hemen stays just before the verb/infinitive, and çok directly precedes güzel when emphasizing “very.”