While making a plot, it doesn't let me enter any more code, I don't get an error message but it doesn't show ">" anymore

Very likely you are just missing a comma in your last command, to get the prompt back (i.e. >) just press Esc and then run this line again but with the missing comma

plot(y, col = "slateblue", type = "l", lwd = 2, xlab = "tiempo", ylab = "colchones (unidades)", main = "Variable a Nivel")

If this doesn't solve your problem, please provide a REPRoducible EXample (reprex) illustrating your issue.

Also, please try to make your questions in English, since it's the preferred language here and by using Spanish you are excluding most people from the conversation thus lowering your chances of getting help.