syukudai wo site kara nemasu.

Japanese often omits the subject when it’s clear from context. In this sentence, the speaker (I/we) is understood. If you needed to be explicit, you could say:

• 私は宿題をしてから寝ます。 (As for me, I will go to sleep after doing homework.)

The particle を marks 宿題 as the direct object of the verb する (“to do”). You normally need を when you “do” something.

• If you replace it with は, you topicalize “homework,” shifting the nuance:
  
  • 宿題はしてから寝ます。 (Speaking of homework, I will do it and then sleep.)
• Using が here would be ungrammatical because が marks the subject, not the object of する.

The construction V-てから means “after doing V.” It links two actions in sequence:

1. 宿題をして (“do homework” in the て-form)
2. から (“after that”)
3. 寝ます (“go to sleep”)

It emphasizes that the first action must finish before the second begins.

• V-てから = “after doing A, then B.” It focuses on sequence and completion of A.
• Vたら = “when/if A happens, then B,” and can express a conditional nuance or a point in time.

Examples:

• 宿題をしてから寝ます。 (I’ll do homework, and only after that will I sleep.)
• 宿題をしたら寝ます。 (Once I finish homework, then I’ll sleep—but it also sounds like a simple temporal/conditional statement, not emphasizing order as strongly.)

Yes, V-て + main verb can show a sequence or just link actions:

• 宿題をして寝ます。 could mean “I’ll do homework and then sleep,” but it’s a bit more casual and the order can feel less rigid.
• してから explicitly marks “after doing” and makes the sequence very clear.

寝ます is the polite (masu) form. In casual speech or writing you can use the plain dictionary form:

• Casual: 宿題をしてから寝る。
• Polite: 宿題をしてから寝ます。

Choose based on how formal you want to sound.

You can also say Vた後(で) to mean “after V.” Both express sequence:

• 宿題をした後で寝ます。
• 宿題をしてから寝ます。

Nuance:

• ～てから often feels more conversational and tightly linked.
• ～た後で can sound a bit more formal or descriptive. Both are correct.