Definition of SMH in English:

SMH

informal
  • Shaking (or shake) my head (used to express disapproval, exasperation, frustration, etc.)

    ‘They'll do anything for ratings. SMH’
    ‘SMH at your silly remarks’
    ‘I can both understand the outrage and SMH at it’
    • ‘Wow smh, so many off-subject arguments and comments.’
    • ‘That man is father of her children, and all she wants to do is embarrass him in front of them. SMH.’
    • ‘The sequels sucked so what makes them think a tv series will work! Smh.’
    • ‘Smh @ her latest selfie.’
    • ‘It likes she does it for attention, smh.’
    • ‘SMH at this nasty show.’
    • ‘Smh. I'm going to need for her to know that she can't go around saying things like this.’
    • ‘Right now I'm so ashamed of my home state, smh.’
    • ‘You let the fake rumours influence your perception of him. SMH.’
    • ‘SMH at the people who post videos on this site.’

Origin

Early 21st century: sometimes also interpreted as short for so much hate.