Heaven is a place of eternal life, in the presence of God.
Heaven in the Bible
Some specific descriptions of this Kingdom as given in the canon of scripture include— (this list is by no means comprehensive):
Seeing God as He is; sharing in his life - 1 Jn 3:2; 1 Cor 13:12; Jn 17:24
Peaceful Conditions on a New Earth — Is. 2:2–4, 9:7, 11:6–9, 27:13, 32:17–18, 33:20–21, 60:17–18, Ez. 34:25–28, 37:26, Zech 9:10, Matt. 5:3–5, Rev. 21
Eternal Rule by a Messiah–King — Ps. 72, Jer 31:33–34, Zech 2:10–11, 8:3, 14:9, Matt 16:27, Rev 21:3–4 an heir of David, Is. 9:6–7, 11:1–5
Bodily perfection — No hunger, thirst, death, or sickness; a pure language, etc. – Is. 1:25, 4:4, 33:24, 35:5–6, 49:10, 65:20–24, Jer. 31:12–13, Ez. 34:29, 36:29–30, Micah 4:6–7, Zeph. 3:9–19, Matt 13:43
Ruined cities inhabited by people and flocks of sheep — Is. 32:14, 61:4–5, Ez. 36:10,33–38, Amos 9:14
Source: WikiPedia