NumPy accurately describes itself as "the fundamental package for scientific computing with Python".
Debian packages
python3-numpy installs the Python 3 modules
python3-numpy-dev installs the C headers to build Python extensions which make use of NumPy functionality.
python-numpy-doc installs the Sphinx documentation.
Maintaining packages which depend on NumPy
Generally, you should Build-Depend on both python3-numpy and dh-sequence-numpy3. The dh-numpy3 helper will make sure that binary packages depend on the correct NumPy ABI for Python extensions (currently python3-numpy2-abi0).
Cross-building support for Python extensions
If you build a Python extension which uses NumPy, you should have the following dependencies in your debian/control file:
Build-Depends: dh-sequence-numpy3, dh-sequence-python3, python3-all-dev:any, libpython3-all-dev, python3-numpy:any, python3-numpy-dev,
This allows you to run NumPy code at build time while ensuring that any Python extensions are built for the correct host architecture.