Das Personal ist freundlich.

Because Personal is a neuter singular noun in German, so its nominative singular article is das.

• das Personal = the staff / the personnel
• grammatical gender here is neuter
• this is something you have to learn with the noun

Even though staff refers to a group of people, the German noun Personal is grammatically singular.

Because das Personal is treated as a singular noun in German.

So the verb must also be singular:

• das Personal ist freundlich = the staff is friendly / the staff are friendly

This can feel strange to an English speaker, because English sometimes treats staff as plural, especially in British English. German does not do that here. With Personal, the normal agreement is singular:

• Das Personal ist sehr hilfsbereit.
• not: Das Personal sind ...

In this sentence, Personal is a collective singular noun. It refers to all the employees as one group.

So:

• das Personal = the staff, the personnel
• it takes singular verb forms

If you want to talk about individual employees instead, German often uses words like:

• die Mitarbeiter = the employees
• die Angestellten = the employees / staff members

For example:

• Das Personal ist freundlich. = The staff is/are friendly.
• Die Mitarbeiter sind freundlich. = The employees are friendly.

Because freundlich comes after the verb ist and works as a predicate adjective.

In German:

• adjectives before a noun usually take endings
• adjectives after verbs like sein, werden, and bleiben usually do not take endings

Compare:

• das freundliche Personal = the friendly staff
  Here the adjective is before the noun, so it takes an ending: -e
• Das Personal ist freundlich. = The staff is friendly
  Here the adjective is after ist, so there is no ending

This is a very common pattern in German.

It is in the nominative case, because it is the subject of the sentence.

Structure:

• Das Personal = subject, nominative
• ist = verb
• freundlich = predicate adjective

So this is a very basic German sentence pattern:

subject + form of sein + adjective

For example:

• Das Essen ist gut.
• Der Raum ist sauber.
• Die Bedienung ist nett.

No. Standard German uses singular agreement with Personal:

• Das Personal ist freundlich.

Using sind would sound wrong in normal standard German, because Personal is grammatically singular.

If you want a plural subject, use a plural noun:

• Die Mitarbeiter sind freundlich.
• Die Angestellten sind freundlich.

Both can refer to people working somewhere, but they are used a little differently.

• das Personal = the staff, the personnel
  This sounds more collective and somewhat more formal or general.
• die Mitarbeiter = the employees / staff members
  This focuses more on the individual people and is clearly plural.

So:

• Das Personal ist freundlich. = The staff is friendly.
• Die Mitarbeiter sind freundlich. = The employees are friendly.

In places like hotels, restaurants, or hospitals, das Personal is very common.

Freundlich is pronounced approximately like FROYNT-likh.

A few tips:

• eu sounds like English oy in boy
• freund- sounds roughly like froynt
• -lich does not sound like English lick
• the ch here is the softer German ich-Laut, a sound made further forward in the mouth

So a rough English-friendly guide is:

• freundlich ≈ FROYNT-likh

Not perfect, but useful for a learner.

Yes, but the verb must still stay in the second position in a normal main clause.

The neutral version is:

• Das Personal ist freundlich.

You could also say:

• Freundlich ist das Personal.

This is grammatically possible, but it sounds marked or literary and puts special emphasis on freundlich. In most everyday situations, learners should stick with:

• Das Personal ist freundlich.

Mostly, freundlich describes people, behavior, service, or tone as friendly, kind, or pleasant.

Common uses include:

• Das Personal ist freundlich.
• Die Verkäuferin ist freundlich.
• Der Service ist freundlich.

It can also describe things in a broader sense, especially in expressions like:

• ein freundlicher Ton = a friendly tone
• ein freundliches Lächeln = a friendly smile

So in this sentence, it naturally describes how the staff behave toward customers or guests.

Yes, absolutely. Sehr means very, and it fits naturally before the adjective:

• Das Personal ist sehr freundlich. = The staff is very friendly.

Other common intensifiers are:

• wirklich freundlich = really friendly
• besonders freundlich = especially friendly
• außergewöhnlich freundlich = exceptionally friendly

So this sentence is easy to build on once you know the basic pattern.