اخر حلقة من المسلسل كانت احسن من اول حلقة.

Because the main noun is حلقة, and حلقة is grammatically feminine. In Arabic, كان agrees with the subject in gender, so with a feminine singular subject you use كانت.

Even though آخر comes first, the real head of the phrase is still حلقة:

• آخر حلقة = the last episode
• head noun: حلقة

So:

• آخر حلقة ... كانت ... = The last episode ... was ...

That is a very common question. Yes, regular adjectives usually come after the noun in Arabic:

• الحلقة الأخيرة = the last episode
• الحلقة الأولى = the first episode

But أول and آخر are very often used in a common fixed pattern before the noun:

• أول مرة = first time
• آخر يوم = last day
• أول حلقة = first episode
• آخر حلقة = last episode

So this sentence uses a very natural and common pattern. You could also say:

• الحلقة الأخيرة من المسلسل كانت أحسن من الحلقة الأولى

That version is also correct.

It appears twice, and it does two different jobs.

1. من المسلسل
   Here من means something like from or of:

   • حلقة من المسلسل = an episode from the series

2. أحسن من
   Here من means than in a comparison:

   • أحسن من = better than

So the same word من can mean different things depending on the structure.

Because أحسن is extremely common in Levantine Arabic for better.

• أحسن من = better than

You may also learn أفضل, which also means better / preferable, but أفضل often sounds more formal or more standard. In everyday Levantine speech, أحسن is very natural.

So:

• كانت أحسن من أول حلقة = it was better than the first episode

In everyday Arabic, expressions like آخر حلقة and أول حلقة are very common without الـ. Even without الـ, they are often understood as definite from context:

• آخر حلقة من المسلسل = the last episode of the series
• أول حلقة = the first episode

Arabic does not always match English the word-for-word. Context often makes the phrase specific enough.

A more explicitly definite version would be:

• الحلقة الأخيرة من المسلسل
• الحلقة الأولى

This is very common in informal Arabic writing. The more careful spelling is:

• آخر
• أول

But in texting, subtitles, social media, and casual writing, people often leave hamzas out and write:

• اخر
• اول

So as a learner, you should recognize both spellings.

Yes, here it clearly means last or final.

It is true that آخر can sometimes mean other / another in some contexts, but with something in a sequence like episodes, days, pages, or chapters, آخر often means last.

So:

• آخر حلقة من المسلسل = the last episode of the series

not

• another episode of the series

Yes, absolutely.

This version is also correct:

• الحلقة الأخيرة من المسلسل كانت أحسن من الحلقة الأولى

That sounds a bit more explicit and a bit closer to Standard Arabic style. The original sentence:

• اخر حلقة من المسلسل كانت احسن من اول حلقة

sounds very natural and conversational.

Yes, you could say كانت أحسن من الأولى if the context is already clear.

Repeating حلقة makes the comparison very explicit:

• أحسن من أول حلقة = better than the first episode

Without repeating it, Arabic can still work:

• أحسن من الأولى = better than the first one

Both are possible. Repeating the noun is just a very normal and clear way to speak.

In the present tense, Arabic usually does not use a word for is in this kind of sentence. So you would say:

• آخر حلقة من المسلسل أحسن من أول حلقة

This means:

• The last episode of the series is better than the first episode

The original sentence has كانت because it is in the past:

• كانت أحسن = was better