To install Python and PyQt5 on Windows using pip, follow these step-by-step instructions:

Step 1: Download Python

1. Go to the official Python website at https://www.python.org/downloads/windows/.
2. Download the latest version of Python for Windows. Choose the appropriate version (32-bit or 64-bit) based on your system architecture. As of my last knowledge update in September 2021, Python 3.9 was the latest version, but newer versions may have been released since then.
3. Run the installer executable that you downloaded. Make sure to check the box that says "Add Python x.y to PATH" during installation, where x.y is the Python version you downloaded. This will make it easier to use Python from the command line.

Step 2: Verify Python Installation

1. Open a Command Prompt by pressing Win + R, typing cmd, and pressing Enter.
2. Type python --version and press Enter. This should display the installed Python version. Ensure it matches the version you installed.

Step 3: Install PyQt5

1. Open a Command Prompt if it's not already open.
2. To install PyQt5, you can use pip, which is the Python package manager. Run the following command:

  pip install PyQt5  

This command will download and install PyQt5 and its dependencies.

Step 4: Verify PyQt5 Installation

1. To verify that PyQt5 is installed correctly, you can create a simple Python script that imports PyQt5 and runs it.Create a new file with a .py extension (e.g., test.py) and add the following code:   

import sys
from PyQt5.QtWidgets import QApplication, QLabel
app = QApplication(sys.argv)
label = QLabel("Hello, PyQt5!")
label.show()
sys.exit(app.exec_())                                           

Save the file and navigate to its location using the Command Prompt.

Run the script using the following command:

  python test.py  

This should open a window with the text "Hello, PyQt5!" displayed.

That's it! You have successfully installed Python and PyQt5 on Windows using pip. You can now start developing PyQt5 applications on your Windows machine.