The فعل مضارع can give the meaning of present and future. Usually the context will help determine which meaning is intended. However, if the context is not clear, or the speaker wishes to make it clear that he is speaking about the future, the particle س is added.
The translation of this particle is flexibale. In some cases it need not be translated; merely translating the verb in the future tense is will be sufficient.
﴿سَيَقُولُ السُّفَهَاءُ مِنَ النَّاسِ﴾
The foolish among the people will say (Mufti Taqi Uthmani)
The fools among the people will say (Dr. Mohsin)
The foolish among the people will say (The Majestic Qur’an)
The word soon can also be added to the translation.
﴿كَلَّا سَيَعۡلَمُونَ ثُمَّ كَلَّا سَيَعۡلَمُونَ﴾
Indeed they will soon know. (Mufti Taqi Uthmani)
Nay, they will come to know! (Dr. Mohsin)
But the will come to know. (The Majestic Qur’an)
The word anon is an old fashioned word which can be used to express the translation on س.
Mawlana Abdul Majid Daryabadi uses this in his translation if the Quran.