Organization settings hold what applies to the whole workspace: its name and logo, the default language, calendar and start of the week, and its locations. Only the workspace owner can open them.
Only the Owner, the person who created the workspace. Open your profile menu, choose Administration, then Organization. Other members do not see Administration in their profile menu.
Click the name to rename the workspace, and use the edit button on the logo to upload a logo of 1 MB or less. The URL is your workspace's address: it is set when the workspace is created and cannot be changed here. See Create your first workspace.
Click Edit defaults, pick the three values, then click Save.

As the screen says, "These defaults affect every member of this organization." Each person can still choose their own Language and Calendar under Preferences in their profile menu, and their own choice wins over the default. See Set your language, calendar and timezone.
It sets the day a week begins in Goals. Recurring goals, such as sprints, OKRs, KPIs and habits, start each weekly period on that day. The setting is applied when a goal is saved, so existing goals keep their periods until you edit them.
Locations are the offices or sites your team works from. Open Administration, then Locations, and click New Location.

The Free plan includes 1 location. Paid plans have no limit. See Pricing.
Only the workspace owner has Administration in the profile menu. If you need a setting changed, ask the person who created your workspace.
Their own choice under Preferences wins over the workspace default. They can switch it themselves in their profile menu, under Preferences.
Not from Organization settings. The URL is set when the workspace is created.
On each location under Locations, and per person under Working hours in their profile settings. If dates or times look off, see Dates look wrong.
Related: Set your language, calendar and timezone · Teams and jobs · Roles and permissions · Plans & billing explained