Usando um arquivo UI do Qt Designer com seu código Python

aula203-qtdesigner/src/main_window.py

@@ -0,0 +1,23 @@
+import sys
+
+from PySide6.QtWidgets import QApplication, QMainWindow
+from window import Ui_MainWindow
+
+
+class MainWindow(QMainWindow, Ui_MainWindow):
+    def __init__(self, parent=None):
+        super().__init__(parent)
+        self.setupUi(self)
+
+        self.buttonSend.clicked.connect(self.changeLabelResult)  # type: ignore
+
+    def changeLabelResult(self):
+        text = self.lineName.text()
+        self.labelResult.setText(text)
+
+
+if __name__ == '__main__':
+    app = QApplication(sys.argv)
+    mainWindow = MainWindow()
+    mainWindow.show()
+    app.exec()