Advanced antenna system (AAS) is a viable option for 5G millimeter-wave (mmWave) applications. AAS single element is favored to be dual-polarized, wideband, high gain, and compact in order to be utilized for 5G antenna arrays. In this paper, a low complexity and low-cost, dual-polarized aperture coupled antenna operating from 24 up to 44 GHz is presented for 5G mmWave applications. A design methodology is developed to innovate the aperture-coupled antenna in mmWave frequencies upgrading with dual-polarized configuration and grid-slotted technique to meet the AAS single-element requirements. The antenna has an overall size of 0.56 lambda(0)x0.56 lambda(0) while the radiating patch size is only 0.39 lambda(0)x0.39 lambda(0) at the lower frequency of the operating band, a wide bandwidth of around 60%, and polarization isolation of better than 35 dB, a promising radiation characteristics with the polarization discrimination of more than 20 dB and average gain of 7dBi at 5G mmWave bands. The performance comparison shows the advantages and novelty of the proposed antenna in terms of bandwidth and gain with a low complexity and low-cost structure compared to the most recent relevant publications. To the author's knowledge, there has been no mmWave aperture-coupled antenna reported in literature with such great performance and simple structure. The proposed antenna element is a suitable candidate as a part of massive MIMO systems for 5G n257, n258, n259, n260, and n261 frequency bands.