The link is broken, but it doesn't matter for your question.

Any genome browser primarily displays the signal of a ChIP-Seq/RNA-Seq experiment ( and also all other -Seq experiments, variants, peaks, repeat-elements, etc etc etc etc).

For ChIP-Seq, what you see by a bar graph is the signal of a particular protein/histone activity at a given genomic location. If you are looking at a bargraph of a FOXA2 ChIP experiment, that means whenever there is a binding of FOXA2 at a genomic location, there will be bars (signals) and the height of bars represents the strength of FOXA2 protein (TF) binding. You need to understand what is the output of a ChIP-Seq experiment and what does it mean by a transcription-factor ChIP-Seq and Histone modification ChIP-Seq, which are two major readouts commonly used to define enhancers/promoters and to gain insights into genome cis-regulation.

So each track measures a different transcription factor or different histone modification signal, hence you see bars appearing at different places. Combinations of different assays are used to define enhancers/promoters etc

A: How to find out whether Chip-seq peaks falls within promoter or enhancer region