horizontal_layout.py

import sys

from PyQt5.QtWidgets import QApplication, QWidget, QHBoxLayout, QPushButton

app = QApplication(sys.argv)

window = QWidget()
window.setWindowTitle('QHBoxLayout')

layout = QHBoxLayout()

layout.addWidget(QPushButton("Left"))
layout.addWidget(QPushButton("Center"))
layout.addWidget(QPushButton("Right"))

window.setLayout(layout)

window.show()

sys.exit(app.exec())