Learn Hardcore Japanese: watasi ha mainiti honyaku no rensyuu wo simasu.

は is the topic-marker particle. It tells the listener that 私 (“I”) is what we’re talking about. In English you’d often translate it as “as for me” or simply leave it out once the topic is clear.

Why is の used between 翻訳 and 練習?

Here の links two nouns, showing that the first modifies the second. 翻訳の練習 literally means “practice of translation.” In English we’d say “translation practice.”

Why do we write 練習をします instead of just 練習する?

練習をします is the polite form, because します is the polite present of する. In casual speech you could say 練習する (“do practice”), but in polite conversation or writing you use します.

What role does the particle を play after 練習?

を marks the direct object of the verb します. Since 練習 is a noun here and you’re “doing” that noun, you attach を and then the verb する/します.

Can I say 翻訳を練習します instead of 翻訳の練習をします?

Yes, 翻訳を練習します is grammatically correct and means “practice translating.” The nuance is almost identical, though some speakers prefer 翻訳の練習をします because it treats “translation practice” as one set phrase.

Why is 毎日 placed where it is, and can its position change?

毎日 is a time-expression meaning “every day.” Time words in Japanese are quite flexible: you can say 毎日、翻訳の練習をします or 私は毎日翻訳の練習をします or even 翻訳の練習を私は毎日します (the last is a bit marked). Placing 毎日 at the front is most common.

Is it necessary to include 私は at the beginning?

No. Japanese often drops the topic if it’s clear from context. You can simply say 毎日翻訳の練習をします once it’s obvious you’re talking about yourself.

Why does the verb appear at the very end of the sentence?

Japanese follows a Subject-Object-Verb (SOV) word order. That means verbs (and the polite ending ます) always come after their objects and modifiers.