Ni sekvas ĉi tiun principon.

Ni means we. Esperanto subject pronouns are very regular:

• mi = I
• vi = you
• li = he
• ŝi = she
• ĝi = it
• ni = we
• ili = they

So Ni sekvas... means that we are the ones doing the action.

In Esperanto, verbs always show tense with a fixed ending. The ending -as marks the present tense.

So:

• sekvas = follow / are following
• sekvis = followed
• sekvos = will follow

A very important point for English speakers: the verb ending does not change depending on the subject. So:

• mi sekvas
• vi sekvas
• li sekvas
• ni sekvas

They all use sekvas in the present tense.

Sekvi is the dictionary form, meaning to follow. The -i ending is the infinitive.

When you actually use the verb in a sentence, you change the ending:

• sekvi = to follow
• sekvas = follow / follows / are following
• sekvis = followed
• sekvos = will follow

So sekvas is just the present-tense form of sekvi.

The ending -n marks the direct object in Esperanto. The direct object is the thing directly affected by the action.

In this sentence, we follow what?
We follow this principle.

So this principle is the direct object, and both the noun and its matching modifier take -n:

• tiu principo = that/this principle
• tiun principon = that/this principle as a direct object

This is a very common pattern in Esperanto:

• Mi vidas la domon. = I see the house.
• Ŝi legas interesan libron. = She reads an interesting book.

Anything describing the noun also agrees with it.

Tiu means that or sometimes that one.
When you add ĉi, it makes it specifically this or this one, meaning something near the speaker or current context.

So:

• tiu principo = that principle
• ĉi tiu principo = this principle

In the sentence, because the phrase is a direct object, both parts change as needed:

• base form: ĉi tiu principo
• object form: ĉi tiun principon

A useful thing to remember is that ĉi often appears with tiu and related words:

• ĉi tie = here
• ĉi tiu = this
• ĉi tio = this thing

Because ĉi is an invariable little word. It does not take endings like -n or -j.

So when the phrase changes, the parts that agree are tiu and principo, but ĉi stays unchanged:

• ĉi tiu principo
• ĉi tiun principon

That is completely normal.

The sentence uses the most common Esperanto word order: subject + verb + object.

• Ni = subject
• sekvas = verb
• ĉi tiun principon = object

So the structure is very similar to normal English: We follow this principle.

Because Esperanto marks the object with -n, word order can sometimes be more flexible than in English. But this sentence uses the straightforward, standard order.

Yes, Esperanto allows some flexibility because the object is clearly marked by -n.

For example, Ĉi tiun principon ni sekvas would still mean We follow this principle.

That said, Ni sekvas ĉi tiun principon is the most neutral and natural order for a beginner to learn first.

Because the sentence refers to one principle, not several.

• principo = principle
• principon = principle as a direct object
• principoj = principles
• principojn = principles as a direct object

So if the sentence were about more than one principle, it would be:

• Ni sekvas ĉi tiujn principojn. = We follow these principles.

A rough pronunciation guide:

• ĉi ≈ chee
• tiun ≈ TEE-oon
• principon ≈ prin-TSEE-pon

A few pronunciation notes:

• ĉ sounds like ch in church
• c sounds like ts
• Esperanto stress is usually on the second-to-last syllable

So:

• SEK-vas
• TI-un
• prin-TSI-pon

Esperanto does have the definite article la, meaning the. But it is not used here because ĉi tiu already identifies the noun clearly as this principle.

Compare:

• la principo = the principle
• ĉi tiu principo = this principle

You normally would not say la ĉi tiu principo. The demonstrative already does the job of specifying the noun.

The base form is ĉi tiu principo.

Then, because it is the direct object, it becomes:

• ĉi tiu principo → ĉi tiun principon

This is a useful habit in Esperanto: when you see a complicated noun phrase, try identifying its basic form first, then see what endings were added for grammar.