Я взял швабру и помыл пол в ванной.

I took the mop and mopped the floor in the bathroom.

Breakdown of Я взял швабру и помыл пол в ванной.

• я: I
• в: in
• и: and
• ванная: bathroom

Questions & Answers about Я взял швабру и помыл пол в ванной.

Why is я used here—could it be omitted?

Yes, я can often be omitted because the verb ending already shows the subject in past tense context (and Russian often drops subject pronouns when it’s clear).

• (Я) взял швабру и помыл пол в ванной. is natural either way.
  Keeping я can add emphasis/contrast (e.g., I did it, not someone else) or can sound a bit more explicit in narration.

What tense is this, and how do взял and помыл show it?

Both verbs are past tense, masculine singular. Russian past tense is formed with -л (plus gender/number endings):

• взял = took (past, masculine)
• помыл = washed (past, masculine)
  If the speaker were female: взяла, помыла. Plural: взяли, помыли.

Why are взял and помыл perfective—what does that imply?