A label widget displays a text string or a bitmap. Options for frames are also valid options for labels, additional options determine what the label displays. The reference documentation for labels is label.
proc push_button {} {
.ent insert 0 "Hello "
}
label .lab -text "Enter name:"
entry .ent
button .but -text "Push Me" -command "push_button"
pack .lab
pack .ent
pack .but