Haec res mihi grata est.

Both haec and res are nominative singular feminine.

They are nominative because res is the subject of the sentence, and haec goes with res and matches it. So the basic structure is:

• haec res = this thing / this matter
• est = is
• grata = pleasing / welcome
• mihi = to me

So haec res is the thing being described.

Good question. Haec can indeed mean different things depending on context.

Here it is feminine singular nominative, because it modifies res, and res is a feminine singular noun.

So here:

• haec res = this thing / this matter

But in other contexts, haec can also be:

• neuter plural nominative/accusative = these things

Latin forms often do more than one job, so you have to use the noun and the sentence context to tell which meaning is intended.

Res is a 5th-declension noun, and it is feminine.

It is one of the most common Latin nouns, and it has a very broad meaning, such as:

• thing
• matter
• affair
• situation
• sometimes even fact or circumstance

In this sentence, it means something like thing or matter.

Its nominative singular form is res, which is exactly the form you see here.

Mihi is the dative singular of ego.

The important point is that Latin often expresses the idea of liking by saying that something is pleasing to someone.

So instead of saying:

• I like this thing

Latin says:

• This thing is pleasing to me

That is why Latin uses the dative for the person affected:

• mihi = to me

This is very common with adjectives like gratus, grata, gratum and also with verbs such as placet.

Because the sentence is not structured as I do something.
Instead, it is structured as this thing is pleasing to me.

So:

• ego would be nominative, used for I
• mihi is dative, used for to me

The subject here is haec res, not I.

So Latin is not saying I like this thing in the same grammatical way English does. It is saying:

• This thing is welcome/pleasing to me

Grata is an adjective meaning:

• pleasing
• welcome
• dear
• agreeable

In this sentence, it means something like pleasing or welcome.

So haec res mihi grata est literally means:

• This thing is pleasing to me
• or This matter is welcome to me

Depending on context, a smoother English translation might be I am pleased by this or I like this matter, but grammatically the Latin is built around grata est.

Because grata has to agree with res.

In Latin, adjectives agree with the nouns they describe in:

• gender
• number
• case

Here, res is:

• feminine
• singular
• nominative

So the adjective must also be:

• feminine
• singular
• nominative

That gives grata.

It does not agree with mihi.
A very common beginner mistake is to think grata should match mihi, but mihi is dative and is not the noun being described by the adjective.

It describes res, not mihi.

You can tell because:

• res is nominative singular feminine
• grata is nominative singular feminine

Those match.

Meanwhile:

• mihi is dative singular

So grata cannot be agreeing with mihi.

The sense is:

• This matter = subject
• is pleasing/welcome = predicate
• to me = dative of the person affected

Because Latin word order is much more flexible than English word order.

A very common neutral Latin pattern is to put the verb near or at the end, especially in simple statements. So:

• Haec res mihi grata est

is perfectly normal Latin.

English usually prefers a stricter order:

• This thing is pleasing to me

But Latin can move words around more freely because the endings show their grammatical roles.

Yes. Latin often allows different word orders without changing the basic meaning.

For example, these would still mean roughly the same thing:

• Mihi haec res grata est
• Haec mihi res grata est
• Grata mihi haec res est

However, word order can change emphasis or style. For example:

• putting mihi early may emphasize to me
• putting grata early may emphasize pleasing/welcome

The version you have, Haec res mihi grata est, is a very natural and straightforward arrangement.

Yes, very common.

Latin often does not use a verb exactly like English to like. Instead, it often says that something is:

• pleasing to someone
• agreeable to someone
• welcome to someone

So gratus esse + dative is a normal way to express that idea.

A learner should get used to this difference:

• English: I like it
• Latin: It is pleasing to me

This is one of those places where translating word-for-word helps you understand the grammar, even if smoother English might sound different.

In classical pronunciation, haec is usually pronounced roughly like haik.

A few notes:

• h is pronounced lightly
• ae is a diphthong, sounding roughly like the ai in aisle
• the final c is always hard, like k

So:

• haec ≈ haik

In later or ecclesiastical pronunciation, ae is often pronounced more like eh, so it may sound different depending on the pronunciation system being used.

Yes. Together they form the idea is pleasing / is welcome.

This is a very common pattern in Latin:

• adjective + esse

So here:

• grata est = is pleasing / is welcome

Because grata is an adjective, the sentence is technically using a linking verb construction, not an action verb. In other words, est links the subject haec res with the description grata.

That is why the sentence feels a little different from English I like this thing.