What you see under the tabs isn't the full standard notation, it's only the rhythmic values of the notes, i.e. the timing of the notes.
In other words, the tabs tell you what notes to play, and the rhythmic figures below tell you when to play them, and for how long.
In any case you can do this in a couple of different ways:
Listen to the original song and read the notes from the tabs. In this case you'll understand the timing of the notes by hearing them in the song, and you can ignore what's below the tabs.
Learn the rhythmic value of those marks -- quarter notes, eight notes, 16th notes, etc. It's not very hard and it'll be very useful. In this case, too, listen to the original song a lot while reading the tabs, that will help you to understand the meaning of the rhythmic figures.