Learn Hardcore Chinese: tā yìbiān zuò fàn, yìbiān gěi māma dǎ diànhuà.

It marks two actions happening at the same time with the same subject. In the canonical pattern you put 一边 before both verbs: 她一边做饭，一边给妈妈打电话. You can also say 她一边做饭，还给妈妈打电话, but don’t leave the second part without any linker.

Can I drop the comma?

Yes. The comma just marks a natural pause. Both 她一边做饭一边给妈妈打电话 and 她一边做饭，一边给妈妈打电话 are acceptable.

Can I use 在/正在 with 一边?

It’s usually unnecessary and can feel redundant. If you do use it, attach it to a verb phrase: 她一边做饭，一边在给妈妈打电话 or 她一边在做饭，一边打电话. Don’t say 她在一边做饭…; 在 should modify the verb, not 一边.

Why is it 给妈妈打电话 and not 打妈妈电话?

打电话 is a verb–object unit (“make a phone call”). The recipient is introduced with 给 (“to”): 给妈妈打电话 or 打电话给妈妈. Saying 打妈妈电话 incorrectly treats 妈妈 as the object of 打.

Is 给 here the verb “to give”?

No. Here 给 functions as a coverb/preposition meaning “to/for” (marking the recipient). The main verb is 打 in 打电话.

Is 打电话给妈妈 equally correct?

Yes. Mainland usage tends to prefer 给妈妈打电话; Taiwan usage commonly has 打电话给妈妈. Both are fine and widely understood.

Can I just say 打给妈妈?

Colloquially, yes, with 电话 omitted: 我等会儿打给妈妈. In careful writing, keep 电话: 打电话给妈妈 or 给妈妈打电话.

Do I need to say 她的妈妈?

Not if it’s obvious the mother belongs to the subject. With close family terms, Chinese often omits the possessor: 给妈妈打电话. If ambiguity is possible, add it: 给她妈妈打电话.

Should I repeat the subject after the comma?

No. The subject applies to both parts: 她一边做饭，一边给妈妈打电话. Don’t say 她一边做饭，一边她给妈妈打电话.

Where do time/place words go?

After the subject and before the verbs: 她今天在厨房一边做饭，一边给妈妈打电话.

Can the two actions have different subjects?

No. 一边…一边… requires the same subject for both actions. If subjects differ, recast: 她做饭的时候，妈妈给她打电话 or 她做饭，同时妈妈给她打电话.

Can I use 着 to show ongoing action?

Yes. The pattern V1着，V2 means “do V2 while V1 is ongoing”: 她做着饭，给妈妈打电话. You can also say 她一边做饭，一边打着电话. One marker of ongoing action is enough—don’t overmark both verbs unless you have a reason.

Can I use a resultative like 做好(饭) in this pattern?

No. 做好 implies a completed result, which clashes with the idea of two ongoing actions. Use plain/durative verbs for 一边…一边…. If completion matters, sequence it: 她做好饭以后，给妈妈打电话.

What’s the difference between 做饭、做菜、煮饭、烧饭?

做饭: cook (a meal) in general; most neutral.
做菜: cook dishes (focus on the dishes).
煮饭: cook rice; regionally can mean “cook a meal,” but in standard Mandarin usually rice.
烧饭: regional (esp. southern), “to cook.”

Can I use 又…又… instead?

No for actions. 又…又… typically links two simultaneous qualities/states (often adjectives): 她又累又饿. For two actions, use 一边…一边…, 同时, or V1着，V2.

Is 边…边… or 一面…一面… okay?

Yes.

Colloquial/concise: 她边做饭边打电话.
More written/literary: 她一面做饭，一面打电话. Meaning is the same as 一边…一边….

Any pronunciation tips here?

一边: 一 is pronounced yì (fourth tone) here: yìbiān (tone-change rule).
妈妈: māma; the second syllable is usually neutral tone.
给: gěi (third tone). 打电话: dǎ diànhuà.

Do I ever need a measure word for “phone call”?

When counting: 打了一个电话/打了一通电话. With a recipient: 给妈妈打了一个电话 or 打了通电话给妈妈 (the latter phrasing is more Taiwan-style).

Can I change the order to highlight one action?

Yes. Word order can shift focus:

Neutral: 她一边做饭，一边给妈妈打电话.
Emphasize calling: 她一边给妈妈打电话，一边做饭.

Chinese doesn’t usually have spaces—why are there spaces/braces here?

They’re just for teaching segmentation and pinyin. In normal writing you’d see: 她一边做饭，一边给妈妈打电话.