Hou die plan eenvoudig.

Here hou means keep, not hold in the physical sense.

Afrikaans hou has several uses depending on context, for example:

• hou vas = hold tight
• hou van = like / love
• hou ... eenvoudig = keep ... simple

So in Hou die plan eenvoudig, hou means keep in the sense of maintain something in a certain state.

It is the imperative form, meaning a command or instruction.

Afrikaans often uses the plain verb form for commands:

• Loop! = Walk!
• Wag! = Wait!
• Hou die plan eenvoudig. = Keep the plan simple.

So this sentence is telling someone to do something.

In Afrikaans commands, the subject is usually left out because it is understood.

So:

• Hou die plan eenvoudig.

really means something like:

• (Jy) hou die plan eenvoudig.

But in a command, jy is normally not said.

English does the same thing:

• Keep the plan simple. not
• You keep the plan simple.

Die is the definite article in Afrikaans, meaning the.

So:

• die plan = the plan

A useful point for English speakers: Afrikaans does not change the article for gender or case. The same die is used very widely.

Compare:

• die man = the man
• die vrou = the woman
• die plan = the plan
• die kinders = the children

Because Afrikaans nouns do not change for case the way nouns do in some other languages.

In this sentence, die plan is simply the direct object of hou, and it stays as die plan.

So the structure is straightforward:

• Hou = keep
• die plan = the plan
• eenvoudig = simple

Afrikaans is usually much simpler than languages that mark objects with special noun endings.

Because it is describing the state that die plan should be kept in.

The pattern is:

• hou + object + adjective

So:

• Hou die plan eenvoudig. = Keep the plan simple.
• Hou dit kort. = Keep it short.
• Hou die kamer skoon. = Keep the room clean.

Here eenvoudig is not modifying the verb directly. It describes die plan.

Because eenvoudig is being used predicatively, not directly before the noun.

Compare:

• die eenvoudige plan = the simple plan
  
  • here the adjective comes before the noun, so -e is added
• Die plan is eenvoudig = the plan is simple
  
  • here the adjective comes after the noun, so it stays eenvoudig
• Hou die plan eenvoudig = keep the plan simple
  
  • same idea: the adjective comes after the noun and stays eenvoudig

This is a very common Afrikaans pattern.

It is best understood here as an adjective functioning as a complement to die plan.

It tells you what the plan should be like:

• the plan should be simple

It is not really describing how someone keeps the plan; it is describing the resulting state of the plan.

That is why this sentence is closer to:

• Keep the plan simple

than to something like:

• Keep the plan simply

Yes. That is a very useful comparison.

• Die plan is eenvoudig. = The plan is simple.
• Hou die plan eenvoudig. = Keep the plan simple.

In the first sentence, you are describing the plan.

In the second sentence, you are telling someone to make sure the plan stays that way.

The natural word order here is:

• Hou die plan eenvoudig.

That is the standard and most idiomatic order.

Afrikaans generally keeps this kind of structure as:

• verb + object + complement

So for a learner, it is best to treat hou ... eenvoudig as a set pattern.

Less natural rearrangements may sound awkward or marked, so Hou die plan eenvoudig is the form you should aim for.

The sentence as given is a normal direct instruction. If you want to soften it, Afrikaans can add words like asseblief or use a slightly less direct phrasing.

For example:

• Hou die plan eenvoudig, asseblief. = Please keep the plan simple.
• Probeer om die plan eenvoudig te hou. = Try to keep the plan simple.

So the original sentence is not rude by itself, but it is a clear command.

Hou is roughly pronounced like English how, though the exact vowel quality is Afrikaans.

A rough guide for the whole sentence:

• Hou ≈ how
• die often sounds like dee
• plan is similar to English plahn
• eenvoudig is roughly AIN-fow-dukh or AIN-fow-dikh, depending on accent and how precisely you pronounce the final sound

A simple learner-friendly approximation would be:

• how dee plahn AIN-fow-dukh

A few very useful ones are:

• Hou dit eenvoudig. = Keep it simple.
• Hou die deur oop. = Keep the door open.
• Hou die kamer skoon. = Keep the room clean.
• Hou dit kort. = Keep it short.
• Hou alles gereed. = Keep everything ready.

These all use the same basic pattern:

• Hou + object + adjective/state

So Hou die plan eenvoudig is a very practical model sentence to learn.