La scie que tu m’as prêtée coupe bien, mais je n’aime pas scier quand il pleut.

In French, singular countable nouns usually need an article.

So la scie means the saw.
Just scie by itself would normally sound incomplete.

Here, la is used because scie is a feminine singular noun:

• un marteau = a hammer
• une scie = a saw
• la scie = the saw

Here, que means that or which in a relative clause.

So:

• La scie = the saw
• que tu m’as prêtée = that you lent me

Together:

• La scie que tu m’as prêtée = The saw that you lent me

French uses que as the direct-object relative pronoun here, because the saw is the thing being lent.

m’ is the shortened form of me.

So:

• tu m’as prêtée = you lent me
• literally: you to-me have lent

French object pronouns like me, te, le, la, nous, vous usually come before the verb:

• tu me prêtes = you lend me
• tu m’as prêtée = you lent me

It becomes m’ instead of me before a vowel sound, to make pronunciation easier.

Because the past participle agrees with the preceding direct object in this structure.

The direct object is que, and que refers back to la scie, which is feminine singular.
So the past participle becomes feminine singular too:

• masculine singular: prêté
• feminine singular: prêtée

That is why French says:

• La scie que tu m’as prêtée

This is a very common point of difficulty for English speakers, because English does not make this kind of agreement.

Because with avoir, the past participle agrees when the direct object comes before the verb.

Compare:

• Tu as prêté la scie.
  Here the direct object la scie comes after the verb, so no agreement is written: prêté

• La scie que tu m’as prêtée
  Here the direct object is represented by que, which comes before the verb, so agreement appears: prêtée

This is a standard written rule in French grammar.

Literally, coupe bien means cuts well.

So:

• La scie ... coupe bien = The saw ... cuts well

French often uses couper this way for tools:

• Ce couteau coupe bien. = This knife cuts well.
• Cette tondeuse coupe mal. = This mower cuts badly.

So coupe bien is a very natural way to say that the saw works effectively.

After aimer, French normally uses the infinitive when talking about liking or not liking an activity.

So:

• j’aime lire = I like reading / I like to read
• j’aime cuisiner = I like cooking / I like to cook
• je n’aime pas scier = I don’t like sawing / I don’t like to saw

That is why French uses scier (the infinitive), not a conjugated form.

They are related, but one is a noun and the other is a verb:

• la scie = the saw
• scier = to saw

So in this sentence:

• La scie ... coupe bien = The saw cuts well
• je n’aime pas scier = I don’t like sawing / I don’t like to saw

English does something similar:

• the saw = noun
• to saw = verb

In il pleut, the il does not refer to a real person or thing. It is just a required subject pronoun.

French needs a subject in a normal sentence, so weather expressions often use il:

• il pleut = it is raining
• il neige = it is snowing
• il fait froid = it is cold

So quand il pleut simply means when it rains.

In standard written French, negation is usually:

• ne ... pas

So:

• je n’aime pas = I do not like

Because aime starts with a vowel sound, ne becomes n’:

• je n’aime pas

In everyday spoken French, many people drop ne, so you will often hear:

• j’aime pas

But in careful writing and standard grammar, je n’aime pas is the expected form.

French normally uses object pronouns before the verb, not after it.

So:

• tu me prêtes la scie = you lend me the saw
• tu m’as prêtée ... = you lent me ...

Using à moi here would sound wrong for this structure.
French prefers the pronoun me / m’ before the verb.

This is one of the big differences from English word order.

They are pronounced differently:

• scie → roughly see
• scier → roughly see-yay

More exactly:

• scie = /si/
• scier = /sje/

That difference matters in the sentence:

• La scie = the saw
• scier = to saw

So even though they look very similar, they are not pronounced the same.

French often drops a vowel before another vowel sound and replaces it with an apostrophe.

So:

• me as becomes m’as
• ne aime becomes n’aime
• je aime becomes j’aime

This is called elision. It is very common in French and helps the sentence sound smoother.

Tu is the informal singular you.

So this sentence sounds like one person speaking casually to a friend, family member, child, or someone they know well:

• que tu m’as prêtée = that you lent me

If the speaker were addressing someone formally or more than one person, French would use vous:

• La scie que vous m’avez prêtée...

So tu tells you something about the relationship: it is informal.