Those objects are not data frames, they are matrices with 6 rows and 2 columns. The numbers in square brackets describe the dimensions of the rows and column. You can make a similar object with
MAT <- matrix(1:12,nrow = 6)
You can transform them into data frames with code like
t1_DF <- as.data.frame(t1)
An important difference between data frames and matrices is that a data frame can have columns of different types. The first column might be text and the second might be numbers. A matrix must contain only one data type.
The points function is used to add data points to a plot that already exists. If you have a question about that, please start another topic since having multiple questions in one topic leads to confusing answers.