Sango estas ruĝa.

• sango = a noun, marked by -o
• estas = the present-tense form of esti (to be)
• ruĝa = an adjective, marked by -a

So the structure is:

noun + to be + adjective

That is a very common Esperanto pattern.

Esperanto has:

• la = the
• no separate word for a/an

So a sentence like Sango estas ruĝa can mean a general statement such as Blood is red.

If you wanted to make it definite, you could say La sango estas ruĝa, but that would usually mean a specific blood sample or some particular blood already being talked about.

Those endings show the part of speech:

• -o = noun
• -a = adjective

So:

• sang-o = blood
• ruĝ-a = red

This is one of the most regular features of Esperanto. English speakers often like it because the endings make sentence structure very clear.

Yes. estas is the present tense of esti, which means to be.

Esperanto verbs are very regular:

• -as = present
• -is = past
• -os = future
• -us = conditional
• -u = command/wish
• -i = infinitive

So:

• estas = am / is / are

Unlike English, Esperanto does not change the verb for different subjects. So:

• mi estas = I am
• li estas = he is
• ili estas = they are

The verb form stays the same.

In this sentence, sango is singular, so ruĝa is singular too.

Adjectives in Esperanto agree with the noun they describe in:

• number
• accusative case, when applicable

So:

• singular: ruĝa
• plural: ruĝaj

For example:

• La pomo estas ruĝa = The apple is red
• La pomoj estas ruĝaj = The apples are red

Here, ruĝa matches singular sango.

No. After esti (to be), the following adjective is not a direct object. It is a predicate adjective, describing the subject.

So:

• Sango estas ruĝa is correct
• Sango estas ruĝan is not correct

The -n ending is used for direct objects and for some other functions, but not after esti in a sentence like this.

No, not in normal Esperanto.

• ruĝa is an adjective: it describes a noun
• ruĝe is an adverb: it describes a verb, adjective, or whole clause

Since blood is being described, you need the adjective:

• Sango estas ruĝa = correct

Using ruĝe would be like saying Blood is redly, which does not work here.

ĝ is pronounced like the j in judge.

So:

• ruĝa sounds roughly like ROO-ja
• sango sounds roughly like SAHN-go

A few useful pronunciation notes:

• u = like oo in food
• a = like a in father
• g = always hard, as in go
• stress is usually on the second-to-last syllable

So the stress is:

• SAN-go
• RU-ĝa
• ES-tas

The normal, most straightforward order is:

subject + verb + complement

So Sango estas ruĝa is the standard way to say it.

Because Esperanto marks word classes clearly, word order can sometimes vary for style or emphasis, but beginners should use the basic order first. In this sentence, Sango estas ruĝa is the natural choice.

Yes. In Esperanto, sango is a regular noun with the normal noun ending -o.

Like English blood, it is usually used as a mass noun, so in a general statement you normally leave it singular:

• Sango estas ruĝa

Even though it is a mass noun in meaning, grammatically it still behaves like an ordinary Esperanto noun.