"Πρόκειται να σε βοηθήσω."
Translation:I am going to help you.
Most sentences with the construction "I'm about to..." are marked wrong in those exercises, contrary to what the "Tips and notes" section indicates. Is there a precise reason for this ?
The Tips & Notes indicates "about to" as "another common translation" however not all translations are suitable in all cases. You'll also note that the main translation is "going to" and all the examples are "going to". In the Drop down hints you'll see only "going to" because in this case, it's the "going to" that has the main meaning.
The Drop down hints are designed to give the main translation first, although alternatives may be provided they are often for other usages.
"About to" portraits the meaning of "immediacy" "I was about to leave the house when I remembered I didn't have my keys." whereas, "going to" is a general idea of something that will happen. Since there is no indication of immediacy in this sentence "going to" is the translation of choice.
I'll add "about to" as an alternative but it sounds odd to my English ear.