אם הכתף שלך כואבת, תנוחי קצת בבית.

In Hebrew, possessors usually come after the noun.

So:

• הכתף שלך = literally the shoulder of yours
• natural English translation: your shoulder

Two useful points:

• Hebrew often says the + noun + שלך/שלי/שלו...
• With body parts, this is especially common: הראש שלי, היד שלך, הגב שלו

There is also a shorter, more literary form like כתפך for your shoulder, but in everyday modern Hebrew, הכתף שלך is much more common.

Because Hebrew often keeps the noun definite even when it is possessed.

So הכתף שלך is literally the shoulder שלך, but it simply means your shoulder.

This is normal Hebrew usage, not something extra-emphatic. English and Hebrew just build possession differently.

Because כתף is a feminine singular noun, and כואב/כואבת agrees with it.

• כתף = feminine singular
• so: כואבת

Compare:

• הגב שלך כואב = your back hurts (masculine noun)
• הכתף שלך כואבת = your shoulder hurts (feminine noun)

So the ending -ת is there because the subject is feminine singular.

Here כואבת functions like hurts / is hurting.

It comes from the verb לכאוב = to hurt / to ache.

Hebrew often does not use a present-tense word for is/are the way English does. So:

• הכתף שלך כואבת
• literally something like your shoulder hurting
• natural English: your shoulder hurts or your shoulder is hurting

So nothing is missing. This is a normal Hebrew sentence.

In modern Hebrew, speakers very often use the future tense form to give commands or advice.

So:

• classical/grammatical imperative: נוחי
• very common modern spoken command/advice form: תנוחי

Both relate to the verb לנוח = to rest.

In everyday speech, תנוחי sounds very natural. It can feel like:

• rest
• you should rest
• go get some rest

The clearest clue is תנוחי.

The ending -י marks second person feminine singular here, so the speaker is talking to one female.

Compare:

• to a man: תנוח
• to a woman: תנוחי
• to several people: תנוחו

A useful detail: שלך by itself is ambiguous in normal unpointed writing, since it can be read as masculine or feminine depending on context. But תנוחי removes the ambiguity here.

קצת means a little, a bit, or somewhat.

In this sentence:

• תנוחי קצת = rest a bit

Its position after the verb is very natural in Hebrew. It works much like English a bit after a verb.

You could move adverbs around in some contexts, but תנוחי קצת is the most straightforward and natural phrasing here.

Yes, literally בבית can mean in the house, but very often it is also the normal way to say at home.

So in this sentence:

• תנוחי קצת בבית = rest a bit at home

This is very natural Hebrew.

Also, Hebrew attaches prepositions directly to nouns:

• ב + בית → בבית

Depending on context, בבית can mean:

• at home
• in the house
• in a house

Here, at home is the natural meaning.

Because Hebrew usually does not need it.

English often says:

• If your shoulder hurts, then rest a bit at home.

Hebrew normally just says:

• אם הכתף שלך כואבת, תנוחי קצת בבית.

So אם ... , ... already gives the full if ... then ... meaning, even without a separate word for then.