what is y and x after test train split pandas dataframe code example

Example 1: pandas split dataframe to train and test

train=df.sample(frac=0.8,random_state=200) #random state is a seed value
test=df.drop(train.index)

Example 2: pandas split train test

from sklearn.model_selection import train_test_split

train, test = train_test_split(df, test_size=0.2)