Xpath preceding

DOM tree

<span lightning-radiogroup_radiogroup="" class="slds-radio_faux"></span>
<span lightning-radiogroup_radiogroup="" class="slds-form-element__label">Yes</span></label>

My XPath

//Label[text()='External']//following::fieldset//span[text()='Yes']

UI design

I want to click the radio button from the above UI, my XPath perfectly located the 'Yes' or 'No'
but unfortunately unable to click the radio button.

From my XPath how can I select the radio button based on the label value (Yes, no)

The problem is that you are selecting the span inside a radio button.

You need to select the radio-button node.
It would be a node similar to this:

<!-- begin snippet: js hide: false console: true babel: false -->

<!-- language: lang-html -->

<input type="radio" name="name" value="NO" >
<label>
    <span lightning-radiogroup_radiogroup="" class="slds-radio_faux">NO</span>
 </label>

 <input type="radio" name="name2" value="Yes">
 <label>
    <span lightning-radiogroup_radiogroup="" class="slds-form-element__label">Yes</span>
 </label>

<!-- end snippet -->

So you need an XPath like this:

//input[@type="radio"]/span[text()="YES"]/preceding::input

Find the Yes text span and then find it's ancestor element here it is label then go to its input element by /ancestor::label/input

"//span[contains(text(), 'Yes')]/ancestor::label/input"

this is sample HTML:

Try

//span[.='Yes']/preceding-sibling::span[@class='slds-radio_faux']

or (most likely)

//span[.='Yes']/preceding::input[@type='radio']