The text, btw, is John 2:19-21.
This is a saying that is interpreted in different ways by different writers. It first appears in Mark 14:58, 15:29 as something that is attributed to Jesus by his opposers before the Sanhedrin; it is not something that Jesus is represented as actually saying. In fact, Mark 14:57 states that such an utterance is a "false witness" about Jesus, and v. 59 adds that the people saying this did not agree in the details. Within the context of Mark, the saying is evidently a misunderstanding of the oracle in 13:1-2 in which Jesus announces as he is leaving the Temple that the building is going to be destroyed (clearly alluding to the destruction of the literal Temple). The other gospels handle this saying in different ways. Luke omits the saying in his version of the Sanhedrin episode (Luke 22:66-71) so that he can use it to compose the parallel story of Stephen's arrest:
"They took Stephen by surprise, and arrested him and brought him before the Sanhedrin. There they put up false witnesses to say, 'This man is always making speeches against this Holy Place and the Law. We have heard him say that Jesus the Nazarene is going to destroy this Place and alter the traditions that Moses handed down to us" (Acts 6:12-14).
Here, as in Mark, the saying is mentioned as something "false" that is used to trump up charges on Stephen. Note also that the Temple is interpreted literally, as it is in Mark. Matthew 26:61 repeats the Sanhedrin episode from Mark with the "I am able to destroy the Temple of God and build it up in three days" saying, but also attributes it to mockers at Jesus' cross in 27:40. John however puts the saying in the mouth of Jesus, in a particular setting (replacing the "you have made the house of God into a den of robbers" saying from Mark 11:17), and gives an explicit spiritualizing interpretation of the saying.
Does Jesus mean that he is going to himself raise his body from the dead, a saying that coheres well with a modalist christology? It's possible, tho it must be admitted that the author is working with a saying unit that preceded him and thus did not originate the notion of Jesus' agency in the raising. Yet there is another parallel in John 10:17-18: "I lay down my life in order to take it up again. No one takes it from me; I lay it down of my own free will, and as it is in my power to lay it down, so it is in my power to take it up again". The saying in John 2:19-21 is also rather close to what Ignatius of Antioch says: "He suffered all these things for our sakes, in order that we might be saved; and he truly suffered just as he truly raised himself (anestésen heauton), not as certain unbelievers say that he suffered in appearance only" (Smyrnaeans 2:1). Elsewhere however he referred to the Father raising Jesus (cf. Trallians 9:2, Smyrnaeans 7:1), and Paul always refers to God raising Jesus, not Jesus raising himself.