Hi @Jyoti Chakraborty ,
In scrum projects you can create a burndown chart by accessing Project menu > Reports > Burndown chart. You can read more about burndown charts in Atlassian docs.
If you're looking to create a burndown chart in kanban projects or across multiple projects it's not available in Jira out of the box but you can have a look at this article for a workaround.
I hope this helps. Nikki