Edit in JSFiddle

Ext.create('Ext.form.Panel', {
        title: 'labelSeparator',
        renderTo: Ext.getBody(),
        items: [{
        	xtype: 'displayfield',
            name: 'table_name',
            fieldLabel: 'Table Name',
            value: 'aaaaa'
        }, {
        	xtype: 'displayfield',
            name: 'column_name',
            fieldLabel: 'Column Name',
            labelSeparator : '',        // use labelSeparator
            value: 'bbbbb'
        }]
    });