The statements you've listed describe a PARLIAMENTARY SYSTEM of government.
In a parliamentary system:
- Voters elect the legislature (the parliament).
- Party with the largest number of elected representatives forms the government. If that party did not have a majority of the total seats in the parliament, that will mean forming a coalition with other parties, in order to have majority support in the government.
- Executive branch receives its authority from the legislature. The leader of the party with the most seats in parliament serves as prime minister, the head of the executive branch.
The Borgen Project provides this helpful summary: "In terms of the U.S. system, a country’s parliament would serve as both its legislative and executive branches."