Near: For each feature in the input layer, the Near tool finds the nearest feature in same or another layer. Adds attributes such as distance to attributes of input table. Works with points, lines, polygons. Online help.
Generate Near Table: A tool similar to above, but creates a new table rather than adding to existing attributes and can handle many-to-one and one-to-many relationships. To limit the number of calculations, using a Search Radius is recommended for large datasets because the output table can get really big.
The table is just a correspondence between the target and the near feature IDs, so typically you will want to Join by Attributes to connect with substantive data. Online help.
Buffer: Creates buffer polygons (a new layer) around input features to a specified distance. An optional dissolve can be performed to combine overlapping buffers. Online help. Also see a more technical discussion of how it works, including a discussion of geodesic buffering used with unprojected geographic coordinate systems (degrees longitude and latitude) and why this might be appropriate.
Multiple Ring Buffer: Creates multiple buffers at specified distances around the input features (i.e., rings around features). These buffers can optionally be merged and dissolved using the buffer distance values to create non-overlapping buffers. Online help.
Polygon Neighbors: Creates a table with statistics based on polygon contiguity (overlaps, coincident edges, or nodes). Online help.
Create Thiessen Polygons: Creates Thiessen polygons (proximal zones or Voronoi cells) from point input features. Any location within a Thiessen polygon is closer to its associated point than to any other point input feature. Online help.
Measure Tool: Access this from the Inquiry Group under the Map tab in the ArcGIS Pro Ribbon. Click on this icon to turn the cursor into this tool. Allows you to measure distances along a line, areas of polygons, and other basic measurements. Some calculations require your map to use a projected coordinate system.
Add Geometry Attributes: This geoprocessing tool adds measurement values to a new field in the layer's attribute table. Includes, depending on the type of feature (points, lines, polygon): Area or Perimeter (polygons), Length (lines) , X- or Y-coordinate of centroid (polygons or lines) or of point, X- or Y-coordinate of start or end point of lines. The Add XY Coordinates tool will do just that for point layers.
Open the Geoprocessing Pane by choosing the Analysis Tab in the Ribbon and clicking on Tools in the Geoprocessing Group.