Rijke landen hebben ook bedrijven.

Because rijk is an adjective placed before a noun, and in Dutch attributive adjectives usually take -e.

• rijk = rich
• het rijke land = the rich country
• rijke landen = rich countries

In this sentence, landen is plural, so rijke is the normal form.

Dutch often leaves out the article with a plural noun when speaking in a general sense, just like English.

• Rijke landen = rich countries, in general
• De rijke landen = the rich countries, a specific group

So Rijke landen hebben ook bedrijven means something general about rich countries, not about one particular set already known from context.

Yes. Landen is the plural of land.

• het land = the country / the land
• de landen = the countries

In this sentence, landen means countries, not pieces of land.

Because the subject is plural: rijke landen.

Dutch present tense of hebben:

• ik heb = I have
• jij/u hebt/hebt = you have
• hij/zij/het heeft = he/she/it has
• wij/jullie/zij hebben = we/you/they have

Since rijke landen is plural, Dutch uses hebben.

This is normal Dutch main-clause word order:

subject + finite verb + other elements

So:

• Rijke landen = subject
• hebben = finite verb
• ook = also
• bedrijven = companies

Dutch main clauses usually put the finite verb in the second position. Here, the subject comes first, so the verb comes right after it.

Ook means also or too.

In this sentence, it adds the idea that rich countries have companies as well. The exact emphasis depends on context, but here it most naturally means something like:

• rich countries also have companies

Dutch ook is very common and often works like English also/too.

Because bedrijven is being used in a general, indefinite plural sense.

• bedrijven = companies
• de bedrijven = the companies

So the sentence is not talking about specific companies already identified. It simply says that rich countries have companies.

The singular is bedrijf.

• het bedrijf = the company / business
• de bedrijven = the companies / businesses

So bedrijven is just the regular plural with -en.

Often yes, but not always exactly. Bedrijf can mean:

• company
• business
• firm
• enterprise

In many contexts, companies is the best translation. But depending on the sentence, businesses may also fit.

A few useful pronunciation points:

• ij in rijke and bedrijven is a common Dutch vowel sound, somewhat like the vowel in some English pronunciations of time, but not exactly the same.
• rijke is roughly REI-kuh
• bedrijven is roughly buh-DRIJ-vun

Also:

• the -e in rijke is usually a weak uh sound
• stress in bedrijven is on the second syllable: be-DRIJ-ven

Yes, but the meaning changes slightly.

• Rijke landen hebben ook bedrijven = rich countries in general also have companies
• De rijke landen hebben ook bedrijven = the rich countries also have companies

With de, you are more likely referring to a specific group of rich countries already known from the context. Without de, it sounds more like a general statement.