data=[x+[0] for x in df_li]

As an AI language model, I do not have access to the data or context of this code snippet. However, based on the syntax, it looks like the code is trying to extract the first element of each list in a pandas DataFrame called "df_li" and store it in a list called "data".

The code uses a list comprehension, where it iterates over each list in "df_li" using the variable "x" and extracts the first element using the indexing notation "[0]". The extracted first element is then appended to a new list called "data".

Note that this assumes that all the elements in "df_li" are lists and have at least one element. If there are any empty lists or lists with no first element, the code may raise an error.