The short answer
HighLevel has no Keap importer, so the move is manual. Export contacts from Keap as a CSV, strip the parentheses and dashes from the phone column, recreate custom fields and tags in HighLevel, then import. Pipelines, campaigns, forms, landing pages and appointment types are rebuilt by hand, following HighLevel's Keap migration guide.
Export from Keap and fix the phone column
HighLevel's guide describes the Keap side as Contacts, People, select the contacts (or Select All), then Export to a CSV file; exports over 1,000 contacts arrive as a download link sent to your email. Custom field settings do not travel with the export, so document each one. HighLevel's CSV import article adds a Keap-specific warning: the phone field in a Keap export uses parentheses and dashes, which HighLevel cannot read. Select the whole phone column in your spreadsheet, remove those characters so only numbers remain, and save as CSV before importing.
Recreate fields and tags, then import
In HighLevel, create each Keap custom field under Settings, Custom Fields with a matching field type before the import, because the importer can only map columns to fields that already exist. Create the tags you used in Keap as well, so segments still work after the move. Then run the contact CSV import and map every column. For deals, the Keap guide describes recreating each pipeline under Opportunities with the same stages and entering deals by hand. For longer deal lists, HighLevel's opportunity CSV import takes an Opportunity Name and Pipeline on each row, with stage, value and status (Open, Won, Lost or Abandoned) as optional columns.
Rebuild campaigns, forms and appointments
Keap campaigns and automation sequences have no import path. Screenshot or write down each one, including triggers, timers and emails, rebuild it under Automation, Workflows and run a test contact through it. Keap landing pages are rebuilt in HighLevel's funnel and website builder and public forms in the form builder, making sure each submission adds the right tags and starts the right workflow. Appointment types become HighLevel calendars with the same duration, availability, location and reminders, and connecting Google or Outlook calendars prevents double booking. Keep Keap running until the new workflows have been tested.
More answers in HighLevel questions. For costs, see GoHighLevel pricing or run the cost calculator.