If someone uses the writing hand emoji, then it usually means that they are taking note of something for future reference.
More often than not, people will write this emoji multiple times in between words.
For example.
Put ✍️ salt in pot ✍️ before ✍️ boiling
As you can see, the comment above reads as if the person is saying the words out loud while they are writing them down.
An example from TikTok.
The example above was posted on a TikTok video of an Italian man who was cooking pasta.
The “joke” here is that the user is setting a future reminder for herself. In this case, the “reminder” is that she should marry into an Italian family for the sake of food.
Most people will use this “meme” in a joking fashion.
For example, they might “take down” a terrible piece of advice. Or they might purposely write down a useless piece of advice.
In other cases, Internet users will use the writing hand emoji to make satirical observations. They might also use it as a tool to mock others.
An example from Twitter.
Here, you can see that this user is mocking herself. Essentially, she is writing a note to her future self. In this case, she is trying to remind herself that she should not be posting all of her emotions on Twitter.
All in all, this is a pretty flexible “meme”. As a result, the meaning of the ✍️ emoji will largely depend on the context.