المفاجأة كانت حلوة فعلا.

A good Egyptian-style approximation is:

el-mofāgaʔa kānet ḥelwa fiʿlan

A few useful notes:

• ال is usually pronounced el- in Egyptian
• ج is usually pronounced like g in go, so مفاجأة has a g sound, not an English j
• ء is a glottal stop, like the little break in uh-oh
• ح is a deeper, breathier h
• فعلا is often heard as fiʿlan or feʿlan in speech

You may also see learners write it informally as el-mofaga2a kanet 7elwa fe3lan.

Because المفاجأة is a feminine noun.

In Arabic, كان changes for gender:

• كان = masculine was
• كانت = feminine was

Since المفاجأة is feminine, the sentence uses كانت.

For the same reason: المفاجأة is feminine, so the adjective also has to be feminine.

• حلو = masculine nice / sweet
• حلوة = feminine nice / sweet

So:

• الولد كان حلو = the boy was nice / cute
• المفاجأة كانت حلوة = the surprise was nice

It gives you the past tense meaning was.

In Arabic, present-tense is / are is usually not said in sentences like this:

• المفاجأة حلوة = the surprise is nice
• المفاجأة كانت حلوة = the surprise was nice

So كانت is the thing that turns the sentence into the past.

Because here حلوة is a predicate adjective, not an adjective directly attached to the noun.

Compare these:

• المفاجأة الحلوة = the nice surprise
  Here, الحلوة describes the noun directly, so it also takes ال.

• المفاجأة كانت حلوة = the surprise was nice
  Here, حلوة is the predicate, so it normally stays indefinite.

This is a very common Arabic pattern: definite subject + indefinite predicate.

Yes, literally حلو / حلوة can mean sweet, but in Egyptian Arabic it is used very broadly to mean:

• nice
• pleasant
• lovely
• good
• sometimes cute

So المفاجأة كانت حلوة sounds very natural in Egyptian and means the surprise was nice / lovely / pleasant, not necessarily sugary-sweet.

فعلا adds emphasis. Depending on context, it can mean:

• really
• truly
• indeed

So:

• المفاجأة كانت حلوة = the surprise was nice
• المفاجأة كانت حلوة فعلا = the surprise was really nice / truly was nice

In Egyptian speech, it is often pronounced fiʿlan or feʿlan.

Yes, you can.

Both are correct:

• المفاجأة كانت حلوة فعلا
• كانت المفاجأة حلوة فعلا

The original version sounds very natural if you are already talking about the surprise and want to comment on it.

Starting with كانت can sound a little more like storytelling or narration, but both are fine.

It works in both, but it sounds especially natural in Egyptian speech.

Why?

• The overall structure is fine in both
• حلوة is understood in both, but in Egyptian it is especially common as an everyday word for nice / lovely
• The pronunciation would differ:
  • Egyptian: g sound in ج
  • Standard Arabic: j sound in ج

So an Egyptian learner can definitely use this sentence, and people will understand it easily.

Because both words end with ة, called taa marbuuTa.

In normal pronunciation at the end of a word, this usually sounds like -a or -ah, not -t:

• حلوة → ḥelwa
• مفاجأة → mofāgaʔa

That is why you do not normally say helwat or mofāgaʔat here.

The t sound can appear in other forms, especially when endings or suffixes are added.

A few useful things:

• It is a feminine noun
• It has ال, so it means the surprise
• It contains a hamza ء, which gives a glottal stop near the end
• In Egyptian, ج is pronounced g

So even though the spelling may look a little heavy at first, the main things to remember are:

• feminine noun
• pronounced with Egyptian g
• brief glottal stop before the final -a