أفكر كثيرا قبل أن أقرر، لكن صديقتي تقرر في دقيقة.

Because أ is the prefix for the first-person singular in the present/imperfect tense in Arabic.

So here:

• أفكر = I think
• أقرر = I decide

In this sentence, the speaker is talking about themself, so both verbs use the I form.

A fully vowelled version would be:

• أُفَكِّرُ = I think
• أُقَرِّرُ = I decide

Notice that in normal Arabic writing, short vowels are usually not written.

كثيرا means a lot or a great deal here.

In this sentence:

• أفكر كثيرا = I think a lot

It is being used adverbially, describing how much the speaker thinks. That is why it appears in the accusative form, often written with tanwīn fatḥ in fully vowelled Arabic:

• كَثِيرًا

So this is not many modifying a noun; it is more like an adverb in English: a lot.

قبل أن means before [someone] does something.

In this sentence:

• قبل أن أقرر = before I decide

This is a very common structure in Arabic:

• قبل أن + present verb

Examples:

• قبل أن أنام = before I sleep / before going to sleep
• قبل أن أخرج = before I go out

So قبل أن أقرر literally means before that I decide, but in natural English we say before I decide.

After أن, the present tense verb normally goes into the subjunctive.

So grammatically, أقرر here is really:

• أُقَرِّرَ

with a final fatḥa in fully vowelled writing.

But in ordinary unvowelled Arabic, that final short vowel is not shown, so it still looks like:

• أقرر

This is very common in Arabic texts: the grammar is there, even when the short vowels are not written.

صديقة means female friend.

When you add my, Arabic attaches the possessive suffix ـي:

• صديقة = a female friend
• صديقتي = my female friend

The ة at the end of صديقة becomes a pronounced t sound when a suffix is added. So:

• صديقة is pronounced roughly ṣadīqa
• صديقتي is pronounced roughly ṣadīqatī

That is why you see ت before ـي.

Because صديقتي is feminine singular, and the present/imperfect verb agrees with it.

So:

• هي تقرر = she decides
• صديقتي تقرر = my friend decides

The prefix تـ is used for she in the present tense.

A fully vowelled form would be:

• تُقَرِّرُ

So the second clause means:

• لكن صديقتي تقرر في دقيقة = but my friend decides in a minute

Both word orders are possible in Arabic, but they can sound slightly different in focus.

Here, لكن صديقتي تقرر puts the emphasis a bit more on my friend:

• but my friend decides in a minute

That works well because the sentence is making a contrast:

• I think a lot
• but my friend decides quickly

So putting صديقتي first after لكن makes the contrast feel clear and natural.

في دقيقة literally means in a minute.

Here it means something like:

• within a minute
• in just one minute
• very quickly

So the idea is not just the clock expression in a minute; it is also emphasizing speed.

Examples:

• أنتهي في دقيقة = I finish in a minute
• أعود في دقيقة = I’ll be back in a minute

In this sentence, it shows how fast the friend makes decisions.

Yes. Normal Arabic writing usually leaves out most short vowels and often also leaves out shadda unless needed.

So the fully vowelled sentence would look more like this:

• أُفَكِّرُ كَثِيرًا قَبْلَ أَنْ أُقَرِّرَ، لَكِنَّ صَدِيقَتِي تُقَرِّرُ فِي دَقِيقَةٍ.

A few useful things to notice:

• أفكر is really أُفَكِّرُ
• أقرر is really أُقَرِّرُ
• تقرر is really تُقَرِّرُ
• the doubled middle consonant in فكّر and قرّر is shown by shadda in fully vowelled text

So if you are only reading unvowelled Arabic, you often have to know the correct verb pattern already.

لكن means but.

It connects the two contrasting ideas:

• أفكر كثيرا قبل أن أقرر = I think a lot before I decide
• لكن صديقتي تقرر في دقيقة = but my friend decides in a minute

So لكن signals contrast, just like but in English.

You may also see the fuller form لكنّ in some contexts, especially before nouns in more formal grammar. In everyday unvowelled writing, لكن is very common.

They come from Form II verbs:

• فكّر = to think
• قرّر = to decide

Form II often has a doubled middle consonant, shown in fully vowelled Arabic with shadda:

• فَكَّرَ
• قَرَّرَ

Their present forms are:

• يُفَكِّرُ / أُفَكِّرُ
• يُقَرِّرُ / أُقَرِّرُ

This is useful because many learners expect the basic dictionary root alone to tell them everything, but Arabic verbs often belong to patterns or forms, and those patterns affect meaning and conjugation.