'Posso fare' tends to refer to something that easily can be done whereas there's a bit of a challenge, and there's more energy going into the accomplishment, when 'Ce la posso fare' or 'C'è' la posso fare' comes into play.

'I can do [it]' or 'I can make [it] may be English equivalents of 'Posso fare'. The verb 'posso' means '[I] am able, [I] can'. The infinitive 'fare' means 'to do, to make'. Together, they're pronounced 'POHS-soh FAH-reh'.

'Ce la posso fare' may mean 'I can do it' or 'I can do it for us'. 'Ce' means 'there' or 'us', depending upon the context. The feminine object pronoun 'la' means 'it'. All together, they're pronounced 'tcheh lah POHS-soh FAH-reh'.

'C'è la posso fare' means something on the order of 'It's [something that] I can do' or 'It's that I can do [it]'. The phrase 'c'è' often is translated as 'there is, there are, etc'.