First off, the "law" is simply a summary proposal and not an actual law.  The President is leaving the details of the law in the hands of Congress.  It may be several weeks -- or even longer -- before a bill is actually signed into law.

The law is targeted at occupations that US Citizens and Permanent Residents do not want to perform -- e.g. janitors, farm workers, and construction laborers.

It remains to be seen if positions where US Citizens and Permanent Residents are in high demand, such as nursing and physical therapy, will be covered by the new law.  About 1 in 9 US nursing positions remain unfilled in the United States.

By all accounts the final law will allow undocumented workers to lawfully work in the US without traveling out of the US.  The administration is carefully not using the word "amnesty." However every proposal we've seen has the characteristics of employment-based amnesty.

The law will likely allow workers to eventually qualify for Permanent Residency  (Green Cards), although applicants may have to return to their native country to obtain their US residency. 

Under the proposal workers will qualify for some Federal benefits, such as Social Security.  Currently many undocumented persons are unable to obtain many federal benefits, usually because of their unlawful status.