What is the meaning of Gleaning?

Something learned by gleaning.

The act of collecting leftover crops from farmers' fields after they have been commercially harvested or on fields where it is not economically profitable to harvest.

The catching of insects and other invertebrates by plucking them from within foliage, or sometimes from the ground. It may also be applied to where prey is picked off, or from within, natural and man-made surfaces such as rock faces and under the eaves of houses.

present participle and gerund of glean

Source: wiktionary.org