Suunnitelma on selkeä ja johdonmukainen.

It breaks down like this:

• suunnitelma = the subject of the sentence, plan
• on = is
• selkeä = clear
• ja = and
• johdonmukainen = consistent / coherent / logical

So grammatically, this is:

subject + verb + predicate adjectives

A very literal structure is:

Plan is clear and coherent.

Finnish does not have articles like English a/an and the.

So suunnitelma can mean:

• a plan
• the plan

Which one is meant depends on context.

That is completely normal in Finnish. Learners often want to add something like the, but Finnish simply does not work that way.

On is the 3rd person singular form of olla, which means to be.

Because the subject suunnitelma is singular, you use:

• suunnitelma on = the plan is

Compare:

• suunnitelma on = the plan is
• suunnitelmat ovat = the plans are

So on is just the normal Finnish equivalent of is.

They are predicate adjectives: adjectives that come after olla (to be) and describe the subject.

Because the subject is singular, the adjectives are in their basic singular form here:

• selkeä
• johdonmukainen

This is different from adjectives that directly come before a noun, such as:

• selkeä suunnitelma = a clear plan

In this sentence, the adjectives are not attached directly to the noun. They come after the verb and describe the subject through the verb on.

It is in the nominative singular.

That is the normal form for the subject of a sentence.

So:

• suunnitelma = nominative singular
• function: subject

In this sentence, nothing special is happening with case. It is the plain subject form.

Johdonmukainen is a very common Finnish adjective meaning something like:

• consistent
• coherent
• logical
• systematic

The best English word depends on context.

In a sentence about a plan, it often suggests that the plan:

• makes sense internally
• follows a clear line of reasoning
• does not contradict itself

So it is a bit more than just clear. A plan can be easy to understand (selkeä) and also well-structured and logically consistent (johdonmukainen).

Yes, it is effectively a compound-type formation, and learners often notice that it looks long.

Historically and semantically, it is related to:

• johdon = of a line / of guidance / of a lead
• mukainen = according to, in accordance with

Together, the idea is something like following a consistent line.

You do not need to analyze it every time you use it, though. In modern Finnish, you should learn johdonmukainen as a normal vocabulary item meaning consistent / coherent / logical.

Yes, Finnish word order is more flexible than English, but the basic order here is the most neutral:

• Suunnitelma on selkeä ja johdonmukainen.

You could also change the order for emphasis, for example:

• Selkeä ja johdonmukainen on suunnitelma.

But that sounds marked or literary, not the most ordinary everyday phrasing.

So for normal use, the best pattern is:

subject + on + description

Because ja means and, and in a simple two-item list of adjectives, Finnish normally does not use a comma:

• selkeä ja johdonmukainen

This is similar to English:

• clear and coherent

A comma would not normally be used here.

The plural version would be:

Suunnitelmat ovat selkeitä ja johdonmukaisia.

Changes:

• suunnitelma → suunnitelmat = plans
• on → ovat = are
• selkeä → selkeitä
• johdonmukainen → johdonmukaisia

This is useful because it shows that predicate adjectives change form too when the subject is plural.

Yes. You can say:

• Suunnitelma on selkeä ja johdonmukainen.
• Suunnitelma on johdonmukainen ja selkeä.

Both are grammatical.

The version with selkeä first may feel slightly more natural if you want to start with the simpler, more immediately noticeable quality and then add the more abstract one. But both are perfectly fine.

A few useful pronunciation points:

• Stress in Finnish is usually on the first syllable.
• Each written vowel is pronounced clearly.
• Double vowels are held longer than single vowels.

Roughly:

• selkeä → SEL-ke-ä
• johdonmukainen → JOH-don-mu-kai-nen

In selkeä, the ending -ä is its own vowel sound, so do not reduce it away.
In johdonmukainen, say all the syllables clearly; Finnish does not usually swallow syllables the way English often does.

Yes. That would mean:

The plan is very clear and coherent.

Here:

• hyvin = very / well

So you can easily add adverbs before the adjectives:

• Suunnitelma on erittäin selkeä ja johdonmukainen. = The plan is extremely clear and coherent.
• Suunnitelma on melko selkeä ja johdonmukainen. = The plan is fairly clear and coherent.

This sentence pattern is very productive in Finnish.