Learn Hardcore Japanese: zimaku ga aru to, nihongo no dorama mo wakakariyasui desu. - With subtitles, Japanese dramas are also easy to understand.

字幕がある = “Subtitles exist / There are subtitles.”
If you said 字幕はある, you’d be topicalizing “subtitles” and adding a contrastive nuance: “As for subtitles, there are (them)… (but maybe something else is missing).”

In this sentence, we just neutrally state the condition “if there are subtitles,” so が is natural.

What does ある mean here, and why isn’t it いる?

Japanese has two basic verbs for “to exist”:

ある – for inanimate things (objects, plants, events, abstract things)
いる – for animate things (people, animals, some personified beings)

字幕 (subtitles) are inanimate, so you must use ある:

字幕がある = “There are subtitles / subtitles exist.”
You cannot say 字幕がいる here; that would sound incorrect.

What is the function of と in 字幕があると、日本語のドラマも分かりやすいです?

Here と is a conditional particle, meaning roughly “when / if”:

字幕があると、… = “When there are subtitles, …” or “If there are subtitles, …”

This と conditional often describes a natural result or a regular outcome:

春になると、暖かくなります。
“When it becomes spring, it gets warm.”

Similarly, 字幕があると、日本語のドラマも分かりやすいです。
= “When/If there are subtitles, Japanese dramas are also easy to understand.”

Why is there a comma after と? Is it required?

The comma after と is mostly punctuation for readability, showing a natural pause between the condition and the result:

字幕があると、日本語のドラマも分かりやすいです。

Grammatically, the comma is not required. You could also write:

字幕があると日本語のドラマも分かりやすいです。

Both are correct; the version with the comma is easier to read, especially for learners.

What does の do in 日本語のドラマ?

の here links 日本語 (“Japanese language”) and ドラマ (“drama”) in an attributive way:

日本語のドラマ literally = “drama of Japanese (language)”
→ more naturally, “dramas in Japanese” or “Japanese-language dramas.”

So X の Y often corresponds to “Y of X” or “X-type Y / Y related to X.”
Here it’s “dramas whose language is Japanese.”

What is the nuance of も in 日本語のドラマも?

も means “also / too / even”, and it implies comparison with something mentioned or implied earlier.

So 日本語のドラマも分かりやすいです suggests:

“(Other things are easy to understand, and) Japanese dramas are also easy to understand.” or
“(Even if other things might be hard,) Japanese dramas are also easy to understand when there are subtitles.”

It presupposes some previously known category (e.g. “non‑Japanese dramas,” “other shows,” “spoken Japanese in general”) and adds Japanese dramas to that group.

Could I say 日本語ドラマ instead of 日本語のドラマ? Is there a difference?

Both appear in real Japanese, but the nuance can differ slightly:

日本語のドラマ
→ strongly “dramas in the Japanese language” (language is emphasized)
日本語ドラマ
→ more like a compound noun; often used like “Japanese(-language) drama” as a category name, e.g. in marketing, listings, titles.

In this specific context—talking about understanding the language—日本語のドラマ sounds a bit more natural because it clearly highlights that the language of the drama is Japanese.

What does 分かりやすい literally mean? How is it formed?

分かりやすい is:

the verb 分かる (“to be understood / to understand” intransitively)
plus the auxiliary adjective やすい (“easy to V / V‑able”).

Formation:

分かる → verb stem 分かり
- やすい
  = 分かりやすい → “easy to understand,” “easy to grasp.”

So:

読む (to read) → 読みやすい (easy to read)
使う (to use) → 使いやすい (easy to use)
見る (to see) → 見やすい (easy to see)

Here, 日本語のドラマも分かりやすいです = “Japanese dramas are (easy to understand).”

Why 分かりやすい and not something like 理解しやすい?

Both are possible, but the nuance is different:

分かる / 分かりやすい
→ everyday, conversational; about something being clear and easy to grasp in a practical sense.
理解する / 理解しやすい
→ more formal, “to comprehend / to intellectually understand,” used in explanations, academic or formal writing.

For TV dramas and subtitles, 分かりやすい sounds the most natural, casual, and common. 理解しやすい would sound more technical or stiff in this context.

Why does the sentence end with です even though 分かりやすい is already an adjective?

In Japanese, い‑adjectives like 分かりやすい can:

Stand alone as a predicate: 分かりやすい。 (“It’s easy to understand.”) – plain/casual.
Or take です after them: 分かりやすいです。 – polite.

です here doesn’t add meaning; it simply makes the sentence polite.
So the structure is:

[Condition] 字幕があると、
[Statement] 日本語のドラマも分かりやすいです。 (polite form)

Could I say 分かりやすくなります instead of 分かりやすいです? What’s the difference?

Yes, but the nuance changes:

分かりやすいです
→ “(They) are easy to understand.” (a general state)
分かりやすくなります
→ “(They) become easy to understand.” (a change, becoming easier)

So:

字幕があると、日本語のドラマも分かりやすいです。
= “With subtitles, Japanese dramas are (in general) easy to understand.”
字幕があると、日本語のドラマも分かりやすくなります。
= “If there are subtitles, Japanese dramas become easy to understand.”
(emphasizes the improvement caused by subtitles)

Can I change the word order to 日本語のドラマも、字幕があると分かりやすいです?

Yes, that is also natural:

日本語のドラマも、字幕があると分かりやすいです。

Japanese word order is flexible. Both:

字幕があると、日本語のドラマも分かりやすいです。
日本語のドラマも、字幕があると分かりやすいです。

are correct.

The second version slightly highlights “Japanese dramas” at the beginning, but the core meaning is the same: with subtitles, Japanese dramas are easy to understand.

How would this sentence look in more casual, everyday speech?

To make it casual, you can:

Drop です → just end with the adjective.
Optionally drop the comma in casual text.

Examples:

字幕があると、日本語のドラマも分かりやすい。
In very casual speech, people might shorten and say something like:
字幕あると日本語のドラマも分かりやすい。
(dropping が; still natural in conversation)

All of these mean the same thing, just with different levels of politeness.