Saya berjalan perlahan di laluan tepi sungai.

The prefix ber- on a root word often turns a noun into an intransitive verb or indicates possession of that noun. Here, jalan means “road” or “way,” and berjalan becomes “to walk” (literally “to have a way” or “to be on the way”).

Malay does not inflect verbs for tense. Time is shown by context or by adding aspect/time words:

• saya berjalan can be present or past.
• To emphasize ongoing action, you can insert sedang: Saya sedang berjalan (“I am walking”).
• For future, you can use akan: Saya akan berjalan (“I will walk”).

perlahan is an adverb (identical in form to the adjective) meaning “slowly.” In Malay, adverbs of manner normally follow the verb they modify:
 • Saya berjalan perlahan = “I walk slowly.”

Both mean “slowly,” but perlahan-perlahan (reduplication) emphasizes a gradual or step-by-step process. It often suggests taking extra time or doing something deliberately:
 • Saya berjalan perlahan = “I walk slowly.”
 • Saya berjalan perlahan-perlahan = “I walk very slowly / bit by bit.”

Breakdown of the phrase:
 • di = preposition “on/at/in.”
 • laluan = “path” or “walkway.”
 • tepi sungai = “side of the river” (literally “river side”).
Put together: di laluan tepi sungai = “on the riverside path.”

Malay has no grammatical articles. Definiteness comes from context or demonstratives (e.g., itu, “that”):
 • laluan = “a/the path,” depending on context.

Malay often omits yang when simply linking nouns or locations. A more formal version could be di laluan yang terletak di tepi sungai, but it’s wordy. Direct juxtaposition—laluan tepi sungai—is preferred.

• jalan = “road/street/way,” typically for vehicles or general “route.”
• laluan = “path,” “lane,” or “walkway,” often narrower or pedestrian-oriented.
  Here, laluan tepi sungai implies a dedicated riverside walking path.

No. jalan on its own is usually a noun. To form the verb “to walk,” you need ber-: berjalan. Omitting ber- makes the sentence ungrammatical.