You can collect the beans (Sensu Beans) by simply finding a small bag of them and walking on it. The sensu beans do not appear in all of the ESF maps. The only official map which has them is esf_riverside.
The sensu beans can restore your like and energy (KI - blue bar). Once you have collected some beans, you can press '9' and either left click to eat one or right click to throw a bean away.