difficulty in understanding c++ function that resolves function names by ordinals

Question

I am following a malware analysis course. And I came across this code which I found confusing. The first two sections make sense but the part where the if statement starts is very difficult for me to understand. This "if" statement is supposed to resolve function names by ordinals. I have put my questions in the comments.

FARPROC WINAPI myGetProcAddress(HMODULE hMod, char * sProcName) {

    char * pBaseAddress = (char *) hMod;

    // get pointers to main headers/structures
    IMAGE_DOS_HEADER * pDosHdr = (IMAGE_DOS_HEADER *) pBaseAddress;
    IMAGE_NT_HEADERS * pNTHdr = (IMAGE_NT_HEADERS *) (pBaseAddress + pDosHdr->e_lfanew);
    IMAGE_OPTIONAL_HEADER * pOptionalHdr = &pNTHdr->OptionalHeader;
    IMAGE_DATA_DIRECTORY * pDataDir = (IMAGE_DATA_DIRECTORY *) (&pOptionalHdr->DataDirectory[IMAGE_DIRECTORY_ENTRY_EXPORT]);
    IMAGE_EXPORT_DIRECTORY * pExportDirAddr = (IMAGE_EXPORT_DIRECTORY *) (pBaseAddress + pDataDir->VirtualAddress);

    // resolve addresses to Export Address Table, table of function names and "table of ordinals"
    DWORD * pEAT = (DWORD *) (pBaseAddress + pExportDirAddr->AddressOfFunctions);
    DWORD * pFuncNameTbl = (DWORD *) (pBaseAddress + pExportDirAddr->AddressOfNames);
    WORD * pHintsTbl = (WORD *) (pBaseAddress + pExportDirAddr->AddressOfNameOrdinals);

    // function address we're looking for
    void *pProcAddr = NULL;

    // resolve function by ordinal
    if (((DWORD_PTR)sProcName >> 16) == 0) { // why shift by 16
        WORD ordinal = (WORD) sProcName & 0xFFFF;   // why & 0xFFFF
        DWORD Base = pExportDirAddr->Base;          

        if (ordinal < Base || ordinal >= Base + pExportDirAddr->NumberOfFunctions)
            return NULL;

        // not sure what this part does
        pProcAddr = (FARPROC) (pBaseAddress + (DWORD_PTR) pEAT[ordinal - Base]);
    }
    ...
    ...
    ...
}

I would very much appreciate some explanation.