She was inundated with good wishes, and so she decided to let her fans know they were all received by the birthday girl.
And in case you didn't already know, Cher really, really, really likes to use emojis. Almost too much.
To anyone without a dirty mind, this is easily read as "Mom had tears in her eyes". Sadly, the internet is full of people with very dirty minds and that "splash" emoji is actually very regularly used to mean... well, semen.
At least someone pointed it out, eventually.
Don't worry, anyone concerned about Cher's mum. There's nothing naughty in her eye.