Apache JMeter is mostly used when we need some number of threads to perform certain operations on different servers like LDAP, HTTP etc.
As most of the servers support secure operation i.e. using SSL (Secure Socket Layer), so we will have to perform SSL operation using jmeter over LDAPS,HTTPS etc.
As JMeter is written in java, so jmeter uses the java keystore known as cacerts. To perform SSL operations using jmeter, you need to add ca self signed certificate of the target server in java keystore.