in arabic 2 particles for future: 1- {سَ} this is used to express about near future, like:إلى العمل غدا = i'll go to the work سَأذهب tomorrow. so if you want to indicate that some thing will happen near or after short period and you're sure from its happening use {سَ}. 2- {سَوْفَ} like: سَوْفَ أُسافِرُ إلى مِصر i'll travel to Egypt in this summer, so, it's used to express about something will happen after a long time and you are not sure that it will be done or you have a doubt or it will already occur but after a long time..

س= you can use it to express an event that will happen very soon in future. سوف = to express an event that will happen in future but it will take time .. in addition to a higher certainty than س according to the context

we use سأ when we will do something right now or after a short time And we use سوف when we will do something after a long time or not now