Munawar
Striving for Paradise
:salam2:
Glad you asked this question. This is just a way people started to write when they write in English.
SWT is an abbreviation of Arabic written in English. The Arabic is "Subhanahu Wa Taala". which can be translated as "Glorious And High".
Similarly you will see e.g. Mohammad (SAW)
The SAW stands for "Sallallahu Alihi Wasalam" which means "Peace Be Upon Him".
Therefore you will also see people writing Mohammad (PBUH)
Wassalam and Good Night my dear sister.