The $4.6 billion jobs bill passed by Congress yesterday and swiftly signed by President Reagan will create employment for several hundred thousand people by pumping additional money--from $1 billion for community development grants to $40,000 for conservation--into scores of existing federal programs.

The legislation, the first major recession-relief measure passed by the 98th Congress, also provides about $200 million in humanitarian aid, such as food and shelter, for the hardest-hit victims of the recession.

Most of the jobs will involve construction, repair and maintenance everywhere from national forests, Indian reservations and fisheries to federal prisons, train stations and veterans' hospitals.

In an attempt to create jobs for women as well as men, Congress provided that up to half the jobs generated through community development block grants will be in the public service area, such as day care for children.

In theory, programs included in the bill were chosen because they are labor-intensive, meaning they provide a high number of jobs for the dollar, and because they can be put in place rapidly, theoretically within 90 days in most cases.

But the programs also include some pet projects of members of the Senate and House appropriations committees, where the legislation was drafted. For instance, his colleagues strongly suspect that House Appropriations Committee Chairman Jamie L. Whitten (D-Miss.) will land the $33 million highway demonstration project for his district.

Roughly $2.1 billion will be targeted to areas of highest unemployment for such projects as federal building repair, park and forest maintenance, mass transit and Amtrak, soil conservation, school construction and military housing. Some of the rest will be parceled out under existing formulas weighted toward areas of poverty and joblessness.