Learn Hardcore Indonesian: Map hijau berisi berkas penting. - The green folder contains important files.

No. In Indonesian, map means a folder or file folder (for papers). A geographical map is peta. So the sentence is about a green folder, not a city map.

Why do the adjectives come after the nouns (map hijau, berkas penting)?

In Indonesian, descriptive adjectives usually follow the noun:

map hijau = green folder
berkas penting = important documents This is the default order: Noun + Adjective.

How do I make it clear whether it’s “a” green folder or “the” green folder?

Indonesian has no articles like “a/the.” Context does the work. To be explicit:

map hijau itu = that/the green folder (definite)
sebuah map hijau = a green folder (one unspecified folder)
map hijau ini = this green folder

How do I show plural “documents”?

Plural is usually inferred from context. To make it explicit:

berkas-berkas penting (reduplication)
beberapa berkas penting = several important documents
banyak berkas penting = many important documents

What exactly does berisi mean, and why not use mengisi?

berisi (ber- + isi “contents”) = to contain, to be filled with. It describes the state of the subject: “The green folder contains…”
mengisi = to fill (something). It needs a direct object and an agent: “He filled the folder with documents” = Dia mengisi map itu dengan berkas. So for “contains,” use berisi, not mengisi.

Could I use mengandung or memuat instead of berisi?

Sometimes, but choose carefully:

mengandung often means “to contain” for substances/abstract content and also “to be pregnant,” so it’s odd with a folder.
memuat is common in publishing/transport contexts (“to carry/include/load”), e.g., “This book contains…” = Buku ini memuat… For a folder holding documents, berisi is the most natural.

Can I say “There are important documents in the green folder” instead?

Yes:

Ada berkas penting di (dalam) map hijau. This focuses on the existence/location of the documents. Map hijau berisi berkas penting focuses on the folder’s contents. Both are fine.

How do I negate the sentence?

Use tidak with the verb, or say it’s empty:

Map hijau tidak berisi berkas penting.
Map hijau tidak berisi apa-apa. = The green folder doesn’t contain anything.
Map hijau kosong. = The green folder is empty.

How do I express past or future (contained / will contain)?

Indonesian verbs don’t change form for tense. Add time markers:

Past: Map hijau tadi/sudah/telah berisi berkas penting.
Future: Map hijau akan berisi berkas penting.

Should I add adalah (Map hijau adalah berisi …)?

No. adalah links two noun phrases (equative sentences). You don’t use it before a verb like berisi. The correct form is simply Map hijau berisi …

Is map capitalized here because it’s a name?

No. map is a common noun. It’s capitalized here only because it starts the sentence. Otherwise, write it lowercase: map.

Is berkas the usual word for “documents”? What about dokumen or file?

berkas = a file/bundle/collection of documents; common in admin/legal contexts.
dokumen = documents (formal, general).
file = common for digital files in everyday speech. In this sentence, berkas penting is natural; dokumen penting is also fine.

Can I say “full of” instead of “contains”?

Yes:

Map hijau penuh (dengan) berkas penting. = The green folder is full of important documents. Use penuh dengan for “full of.” Don’t say “berisi dengan.”

How do I pronounce the words?

Approximate English-like hints:

map: “mahp” (a as in father, short), final p unreleased
hijau: “hee-jow” (ow as in cow)
berisi: “buh-REE-see”
berkas: “buhR-KAHS” (r tapped)
penting: “puhn-TEENG” (ng as in sing)

Could I say map yang hijau instead of map hijau?

map hijau is the normal descriptive phrase “green folder.”
map yang hijau means “the folder that is green,” used when distinguishing it from other folders or adding a relative clause, e.g., map yang hijau itu berisi … You can also say map yang berwarna hijau (the folder that is green-colored) for emphasis or clarity.