Η πιλότος μίλησε ήρεμα και όλοι ένιωσαν καλύτερα.

Because some Modern Greek nouns for professions keep the same noun form for both men and women. The article shows the gender:

• ο πιλότος = the male pilot
• η πιλότος = the female pilot

So the ending -ος does not always mean the person is male.

Greek uses the definite article very often when talking about a specific person or thing. So:

• η πιλότος = the pilot
• μια πιλότος = a pilot

In this sentence, we are talking about a specific pilot, so η is natural.

μίλησε is the aorist form of μιλάω / μιλώ (to speak, to talk).

Here it means a simple completed past action:

• μίλησε = spoke
• μιλούσε = was speaking / used to speak

So Η πιλότος μίλησε ήρεμα presents her speaking as one complete event in the past.

Because ήρεμα is an adverb, and it describes how she spoke.

• ήρεμη = calm, feminine adjective
• ήρεμα = calmly, adverb

So:

• Η πιλότος ήταν ήρεμη = The pilot was calm.
• Η πιλότος μίλησε ήρεμα = The pilot spoke calmly.

A good rule: if the word describes the verb, you usually need the adverb.

όλοι literally means all or all of them. In context, it often matches English everyone.

So:

• όλοι ένιωσαν καλύτερα = everyone felt better / all of them felt better

Greek is using a plural idea where English often uses the singular-looking word everyone.

The masculine plural is the normal default form for a mixed group or for a group whose gender is not being emphasized.

• όλοι = all / everyone (mixed group or unspecified)
• όλες = all (all-female group)

So if the group included men and women, or if Greek is speaking generally, όλοι is the expected form.

ένιωσαν is the 3rd person plural aorist of νιώθω (to feel).

So it means:

• ένιωσαν = they felt

Greek often leaves subject pronouns out, because the verb ending already shows the person and number. In this sentence, the subject is stated as όλοι, so no separate word for they is needed.

Here καλύτερα means better and works adverbially with ένιωσαν.

This is very common in Greek after verbs like νιώθω and αισθάνομαι:

• Νιώθω καλύτερα. = I feel better.

The forms καλύτεροι / καλύτερες are adjectives and would need to agree with a noun. But in this sentence, Greek normally uses καλύτερα.

Not completely. Greek word order is more flexible than English.

This sentence has a very natural, neutral order:

• Η πιλότος μίλησε ήρεμα και όλοι ένιωσαν καλύτερα.

But Greek can move words around for emphasis, for example:

• Ήρεμα μίλησε η πιλότος... = It was calmly that the pilot spoke...

The original order is the most straightforward one for learners.

A simple approximate pronunciation is:

• Η πιλότος → ee pee-LO-tos
• μίλησε → MEE-lee-se
• ήρεμα → EE-re-ma
• και → ke
• όλοι → O-lee
• ένιωσαν → EN-yo-san
• καλύτερα → ka-LI-te-ra

Also, the accent mark in Greek shows you which syllable is stressed:

• πιλότος
• μίλησε
• ήρεμα
• όλοι
• ένιωσαν
• καλύτερα