Kita berlatih di taman setiap petang.

• berlatih is an intransitive verb meaning “to practice” (you practice yourself).
• melatih is a transitive verb meaning “to train” someone else (you train another person).
• latihan is a noun meaning “practice” or “exercise.”
  Since the sentence describes the act of practicing (doing the practice oneself), berlatih is the correct choice.

The prefix ber- on a root verb often indicates:
• an intransitive action or state (no direct object)
• a habitual or ongoing activity
Examples:
• berjalan = “to walk”
• bermain = “to play”
• berlatih = “to practice”

di is the simple locative preposition meaning “at,” “in,” or “on.” It always precedes the noun without attaching as a suffix.
• di taman = “at the park” / “in the park”

Malay does not have definite or indefinite articles (like “a,” “an,” or “the”). Nouns stand by themselves.
Context or demonstratives indicate specificity:
• taman = “a/the park” (context tells you which)
• taman ini = “this park”
• taman itu = “that park”

Malay word order is fairly flexible, but common patterns are:
Subject – Verb – Object/Location – Time
So Kita berlatih di taman setiap petang follows S–V–Loc–Time.
You can also front the time phrase for emphasis:
• Setiap petang, kita berlatih di taman.

Words like setiap (“every”/“each”) always take a singular noun in Malay. You never pluralize that noun.
• setiap petang (correct)
• setiap petangs or setiap petang-petang (incorrect)

Yes, Malay often omits pronouns when context makes the subject clear. In casual speech or if you’re already talking about yourself and others, you could say:
• Berlatih di taman setiap petang.
However, including kita makes it explicit “we.” Omission is common when instructions or schedules are understood without restating the subject.