Necesito unas tijeras y una regla para cortar el papel bien.

In Spanish, tijeras is normally used in the plural, just like scissors in English. So Spanish says unas tijeras for a pair of scissors.

Even though English often uses a pair of..., Spanish usually just uses the plural noun with a plural article:

• unas tijeras = a pair of scissors / some scissors

You may sometimes hear una tijera in certain contexts or regions to mean one blade or one cutting tool, but for ordinary scissors, unas tijeras is the standard choice.

Because the nouns have different grammatical number:

• tijeras is plural, so it takes unas
• regla is singular, so it takes una

So:

• unas tijeras = a pair of scissors / some scissors
• una regla = a ruler

This is just normal article agreement in Spanish: the article must match the noun in gender and number.

Spanish often drops subject pronouns when they are not needed. The verb form already tells you who the subject is.

• Necesito = I need

Because necesito is the yo form, Spanish usually does not say yo necesito unless the speaker wants emphasis, contrast, or clarity.

For example:

• Necesito unas tijeras. = I need some scissors.
• Yo necesito unas tijeras, no él. = I need some scissors, not him.

Para often means for or in order to. After para, Spanish commonly uses an infinitive when the subject stays general or is the same as the main verb.

So:

• para cortar = to cut / in order to cut

In this sentence:

• Necesito unas tijeras y una regla para cortar el papel bien.
• Literally: I need some scissors and a ruler to cut the paper well.

Spanish uses the infinitive cortar here just as English uses to cut.

Spanish uses the definite article more often than English. In many cases where English says just paper, Spanish naturally says el papel.

Here, el papel refers to the material or the piece of paper being cut, and Spanish prefers the article:

• cortar el papel = cut the paper

Saying just cortar papel is possible in some contexts, but it sounds more general, like to cut paper as an activity or type of work, not necessarily a specific piece of paper in front of you.

Bien means well, and in this sentence it modifies cortar.

Spanish often places adverbs like bien after the verb phrase:

• cortar el papel bien = cut the paper well

That word order is natural. You could also hear:

• para cortar bien el papel

Both are correct. The difference is mostly about emphasis and rhythm:

• cortar el papel bien focuses a little more on doing the cutting well
• cortar bien el papel places bien closer to cortar

Yes, you can. Both are possible, but there is a small difference in feel.

• Necesito unas tijeras y una regla... sounds like I need some scissors and a ruler
• Necesito tijeras y una regla... sounds a bit more like I need scissors and a ruler

Including unas can make the sentence sound slightly more complete or specific. Omitting the article is also common, especially when talking about objects you need in a general sense.

Yes. In Spain, regla is the normal everyday word for a ruler used for measuring or drawing lines.

So:

• una regla = a ruler

Be aware that regla can also have other meanings in different contexts, such as rule, and in some contexts it can also refer to menstruation. But in a sentence with school or craft items like tijeras and papel, una regla clearly means a ruler.

Y means and.

In this sentence:

• unas tijeras y una regla = some scissors and a ruler

A useful pronunciation/spelling point: y changes to e before words that begin with an i sound.

For example:

• padre e hijo = father and son
• España e Italia

But here the next word is una, so it stays y:

• tijeras y una regla

Yes. In English, scissors is already plural, so translation depends on context.

• unas tijeras can mean a pair of scissors
• In looser English, it may also be rendered as some scissors

In practice, if you are talking about one normal tool, unas tijeras usually corresponds to a pair of scissors.

Yes, but the meaning changes slightly.

• cortar = to cut
• recortar = to cut out / trim / cut into shape

So:

• para cortar el papel bien = to cut the paper well
• para recortar el papel bien = to trim or cut out the paper neatly/well

If you simply mean cut, cortar is the safest choice. If you mean shaping or trimming paper, recortar may be better.

Yes, it is natural in Spain. It sounds like a normal sentence.

A few natural alternatives are also possible, such as:

• Necesito unas tijeras y una regla para cortar bien el papel.
• Necesito tijeras y una regla para cortar el papel bien.

All of these are understandable and natural. The original sentence is perfectly fine.