When two of your pages target the same search, Google has to pick one, and it often switches between them. Neither builds up the clicks and links to rank well. You've split your own vote. That's cannibalization.

How the report finds it

Open Cannibalization. It reads the last 28 days of Search Console data and lists a search when it had at least 50 impressions and at least two of your pages each got 10 or more of them (and at least 10% of the total). Cases are grouped by the pages involved, biggest first.

Searches for your own brand name are left out. Several of your pages showing up for your name is normal.

What it says for ieltsbandlift.com

0 cases, out of 109 searches checked. Every search leads to one page.

For a small site that's both good news and expected: a search needs 50 impressions before it even qualifies, and few of ours have that yet. We're more likely to create the problem than to have it already. We've just written a speaking practice guide (lesson 7.5), three programmatic speaking-topic pages (lesson 4.4), and we already have a "Band 9 Speaking Part 2" page. That's five pages about IELTS speaking.

Don't create it in the first place

Most cannibalization is self-made, by writing a second page for a search you already have one for. Before writing anything new:

Check the Content Planner's "covered" label (lesson 2.4). If you already cover the topic, improve that page instead (lesson 5.1).
Give each page its own intent. Our speaking pages are fine together because they answer different searches: how to practise, Part 2 answers, hometown questions, travel questions. Two pages both answering "how to practise IELTS speaking" would not be.
Link them to each other with clear anchor text, so Google sees one family of pages with distinct jobs, not rivals.

When a case does show up

The first page listed in each case is the one Google prefers (most clicks, then best position). Usually you make that the one page for those searches:

Merge and redirect: move anything useful from the other page into the main one, then 301-redirect the other page's URL to it.
Refocus: if the other page has a genuinely different purpose, rewrite it around that, change its title, and link from it to the main page.

Check the searches before merging. Two pages for different intents (a guide and a pricing page, say) can both appear for one search without anything being wrong.

Done when

You know the thresholds, and why a small site's report is often empty
Before writing a new page, you check whether you already have one for that search
Every page in a cluster has its own intent, and they link to each other
You know when to merge and redirect, and when to refocus instead