kono zidai wo sitte imasu.

That is a very common question.

With many verbs, -ている does mean an ongoing action, like 食べています = is eating.

But 知る is different. 知る means something like to come to know or to learn. Once that happens, the result is a state of knowing. So:

• 知る = come to know
• 知っている = be in the state of knowing = know

So 知っています is the polite form of 知っている, and it naturally means know, not am knowing.

を marks the direct object of the verb.

Here, the verb is 知っています (know), and the thing being known is この時代.

So:

• この時代 = this era / this period
• を = marks it as the thing known
• 知っています = know

In other words, この時代を知っています means that this era/period is what the speaker knows.

Japanese often leaves out the subject when it is understood from context.

So this sentence could mean:

• I know this era
• She knows this era
• They know this era

The exact subject depends on the situation.

In English, you usually need to say the subject. In Japanese, you often do not.

この means this, and it must come directly before a noun.

時代 means era, age, or time period.

So この時代 means:

• this era
• this age
• this period

The most natural English choice depends on context. If the sentence is about history, this period or this era is often best.

It is read:

この じだい を しっています。

In kana: この じだい を しっています。

A few notes:

• 時代 = じだい
• 知って = しって
• the small っ in しって makes a brief pause before the t sound

So しっています sounds roughly like sheet-teh ee-mas, though it is best to learn it from native audio if possible.

Because 知っています is the usual way to say know as a current state.

If you say 知ります, it does not normally mean I know in the simple present way English does. It is more like will come to know, learn, or it appears in certain specific contexts.

So for the meaning know, Japanese normally uses:

• 知っている
• 知っています (polite)

This is one of the important verbs where the English translation does not match the most basic-looking Japanese form.

Yes, it is grammatical and understandable.

However, the nuance can depend on context.

この時代を知っています can sound like:

• being familiar with that era
• knowing that period firsthand
• knowing what that age was like

If you want to say I know about this historical period, Japanese often uses slightly fuller expressions such as:

• この時代について知っています。 = I know about this era.
• この時代のことを知っています。 = I know about this era.

So the original sentence is fine, but in real conversation, a longer version may sometimes sound more explicit.

Normally, no.

知る / 知っている is a transitive verb, so the thing known is usually marked with を.

So this is the normal pattern:

• X を 知っている = know X

Using が here would generally not be correct for the direct object.

You might see other particles if the sentence structure changes, such as:

• この時代は知っています。 = As for this era, I know it.

But that is different from simply replacing を with が.

This is another very common learner question.

• 知っています = know, be acquainted with, have knowledge of
• 分かります = understand, make sense, be clear

So:

• この時代を知っています。 = I know this era / I know about this period.
• この時代の大切さが分かります。 = I understand the importance of this era.

In short:

• use 知っています for having knowledge
• use 分かります for understanding

知っています is polite ます form.

Compare:

• 知っている = plain
• 知っています = polite

So if you are speaking politely to someone, 知っています is the normal choice.

The sentence is not extremely formal, but it is polite and standard.

Those spaces are usually just for learners.

Normal Japanese writing would be:

この時代を知っています。

Japanese is not normally written with spaces between words the way English is. Textbooks and beginner materials sometimes add spaces to make the structure easier to see.